Heath ID-4801 EPROM programmer

[Lee Hart]

Hi Gang,

I happened to notice a Heath ID-4801 EPROM programmer on eBay. I had
never run across this product before. Naturally, the seller doesn't have
the manual or any docs, and has no idea if it works. (That doesn't stop
him from asking Top Dollar for it anyway.)

But I'm curious. Are any of you familiar with it? What's it program? is
a manual available? The attractive thing about a Heath EPROM programmer
is that it should be "open source" enough to see how it works, so I
could add newer chips to it.

PS: My main EPROM programmer right now is a Valley Data Sciences
VDS-150+, which is an accessory for the H89! :-) It is in a cabinet
styled like the H89. The EPROM socket area is where the keyboard of an
H89 is. An H77 drive enclose can sit on top of it, so the "stack" of the
programmer and H77 match the profile of the H89. It connects to the H89
with an interface card that plugs into one of the I/O slots.

It's a nice programmer, but of course they are out of business, and only
supplied "closed source" software and hardware. No schematics, and no
way to upgrade it. It can't program any parts newer than about 1985.

--
Ring the bells that still can ring
Forget your perfect offering
There is a crack in everything
That's how the light gets in.
-- Leonard Cohen, from "Anthem"
--
Lee Hart's EV projects are at http://www.sunrise-ev.com/LeesEVs.htm

[Dave McGuire]

On 04/11/2014 07:16 PM, Lee Hart wrote:
> I happened to notice a Heath ID-4801 EPROM programmer on eBay. I had
> never run across this product before. Naturally, the seller doesn't have
> the manual or any docs, and has no idea if it works. (That doesn't stop
> him from asking Top Dollar for it anyway.)
>
> But I'm curious. Are any of you familiar with it? What's it program? is
> a manual available? The attractive thing about a Heath EPROM programmer
> is that it should be "open source" enough to see how it works, so I
> could add newer chips to it.

I had one for a long time, and I *may* actually still have one
somewhere. (that'd make more sense if you were to see my place ;))
It's a good programmer. Nice and compact, good user interface.

The bad thing is that it takes personality modules. They are 24- or
28-pin DIP headers (I don't recall which) with jumper wires between pins
to route signals around to the right pins on the instrument's main ZIF
socket.

I don't recall how high it goes, but I programmed 2716s with mine
years ago.

Repairing a 4801 should border on the trivial, if it doesn't work.
Overall I'd say it's a very nice programmer to have.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

[Jack Rubin]

> It's a nice programmer, but of course they are out of business, and only
> supplied "closed source" software and hardware. No schematics, and no way
> to upgrade it. It can't program any parts newer than about 1985.
>
> --

Has anything interesting happened since 1985?
Jack

[steve shumaker]

one should probably define "interesting" before taking on THAT one........

steve

[Glenn Roberts]

I've got one including all that came with it, manual, illustration pack,
etc.

As I recall, back in the days of REMark the payment for writing an article
was you got to order a kit? Or was it when you contributed HUG software?.
I can't remember the details, were there only certain kits? Or maybe was it
just a certain amount off purchase? Anyway I wrote a number of REMark
articles and added at least one utility to the HUG library back then and as
I recall the EPROM programmer was my payment. It still works. Even has an
in circuit emulation mode as I recall. I built a number of personality
modules for it.

- glenn

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[Terry Gulczynski]

Like Glen, I also have a working unit with all of the associated
paperwork and several modules for various EPROMs. I also have the
memory expansion modules so it can handle the max allowable EPROM: 16K
(27128.)

The base unit came with 2K of RAM. The 8K memory expansion option added
6K to the base 2K; the 16K expansion added an additional 8K.

I took the time a long time ago to read and disassemble the internal
EPROM that supplied the Z80 code. I was most impressed with the
machine's ability to run the program without any use of RAM - ALL 16K of
RAM was dedicated to the EPROM image (no CALL/RET, no RST, no PUSH/POP -
it was quite well done.)


Terry

[Lee Hart]

Glenn Roberts wrote:
> I've got one including all that came with it, manual, illustration pack,

> etc... As I recall, back in the days of REMark the payment for writing an article
> was you got to order a kit...

That's pretty cool! It sounds like something Heath would do, too.

Glenn, could I get a copy of the manual? Or maybe we can get it scanned?
I'd be a lot more likely to buy one if I had the manual for it.

Or, I've built a few "Heathkits" from scratch, just from the manual.
Their manuals were that good! Do you think this EPROM programmer would
be a candidate for that?

I get frustrated because I've had 3 "new" EPROM programmers that all
worked for a while, but are now dead or unreliable. Only the old
Heath/VDS programmer still works. And it would be fine, except without
schematics or open-source software, it can't be fixed or new chips
added, either.

What I want is a programmer that I can a) add new parts to as needed,
and b) repair if needed. The Heath ID-4801 might be just such a
programmer. :-)

[Dave McGuire]

On 04/11/2014 09:28 PM, Lee Hart wrote:
> What I want is a programmer that I can a) add new parts to as needed,
> and b) repair if needed.

Not to dissuade you from pursuing an ID-4801...but if you want to "cut
to the chase" and just solve the problem of needing a good device
programmer once and for all, you really can't go wrong with a Data I/O
UniSite. Over twenty thousand devices (!) in the database with the
current software, and it doesn't have any silly work-impeding software
vendor dependencies. In fact it's a completely standalone system,
requiring only a serial terminal to get work done.

For "fun" or for hacking on it, it's not the right answer...but if you
want a serious TOOL to get work done, which will not let you down, this
is your unit.

[Lee Hart]

Dave McGuire wrote:
> Not to dissuade you from pursuing an ID-4801...but if you want to "cut
> to the chase" and just solve the problem of needing a good device
> programmer once and for all, you really can't go wrong with a Data I/O
> UniSite.

Data I/O makes great programmers. We used them at work. But, they are
also very expensive.

I don't need a "production" EPROM programmer. I just need to make a few
occasionally. A backup or replacement part for an old computer (like the
H89), or to patch a ROM for an old SBC (like to fix the date on my Radio
Shack model 100), or for a new project (like the Name Tag I made for
Herb Johnson at the VCF show).

> Over twenty thousand devices (!) in the database with the
> current software, and it doesn't have any silly work-impeding software
> vendor dependencies. In fact it's a completely standalone system,
> requiring only a serial terminal to get work done.

That's the right idea. :-) I also trust that Data I/O actually *tested*
the devices.

I have a Chinese "Genius G540" that also claims a zillion parts. In
reality, it's obvious they never tested 99% of them. It won't program
them, and when I check the voltages, it has the wrong programming
voltages and pulse durations. And there's nothing I can do about it.

For me, this stuff is a hobby. Ideally, I would want to read the data
sheet for the chip to be programmed, set the programmer for the right
pinouts, pulse voltage and duration, load the data in some generic
format (like an Intel hex file), and PROGRAM it.

That's why I found the Heath appealing. It sounds like that's pretty
much what it does!

[Lee Hart]

Terry Gulczynski wrote:
> Like Glen, I also have a working unit with all of the associated
> paperwork and several modules for various EPROMs. I also have the memory
> expansion modules so it can handle the max allowable EPROM: 16K (27128.)
>
> The base unit came with 2K of RAM. The 8K memory expansion option added
> 6K to the base 2K; the 16K expansion added an additional 8K.
>
> I took the time a long time ago to read and disassemble the internal
> EPROM that supplied the Z80 code. I was most impressed with the
> machine's ability to run the program without any use of RAM - ALL 16K of
> RAM was dedicated to the EPROM image (no CALL/RET, no RST, no PUSH/POP -
> it was quite well done.)

That is indeed impressive. Clever work! Though I wonder why they didn't
just add a little RAM for stack and working space?

I like that it uses a Z80. I'm already thinking I could build it with a
Z180 to get a bigger memory space, and thus allow it to program bigger
parts. :-)

Could the ID-4801 program any of the "odd" EPROMs that Heath used in the
H8 or H89? Such as the 3-supply TI TMS2732, or the fusible-link PROMs
like the 444-61?

[Dave McGuire]

On 04/11/2014 10:00 PM, Lee Hart wrote:
>> Not to dissuade you from pursuing an ID-4801...but if you want to "cut
>> to the chase" and just solve the problem of needing a good device
>> programmer once and for all, you really can't go wrong with a Data I/O
>> UniSite.
>
> Data I/O makes great programmers. We used them at work. But, they are
> also very expensive.

True.

> I don't need a "production" EPROM programmer. I just need to make a few
> occasionally. A backup or replacement part for an old computer (like the
> H89), or to patch a ROM for an old SBC (like to fix the date on my Radio
> Shack model 100), or for a new project (like the Name Tag I made for
> Herb Johnson at the VCF show).
>
>> Over twenty thousand devices (!) in the database with the
>> current software, and it doesn't have any silly work-impeding software
>> vendor dependencies. In fact it's a completely standalone system,
>> requiring only a serial terminal to get work done.
>
> That's the right idea. :-) I also trust that Data I/O actually *tested*
> the devices.
>
> I have a Chinese "Genius G540" that also claims a zillion parts. In
> reality, it's obvious they never tested 99% of them. It won't program
> them, and when I check the voltages, it has the wrong programming
> voltages and pulse durations. And there's nothing I can do about it.
>
> For me, this stuff is a hobby. Ideally, I would want to read the data
> sheet for the chip to be programmed, set the programmer for the right
> pinouts, pulse voltage and duration, load the data in some generic
> format (like an Intel hex file), and PROGRAM it.

Sounds good. This is work for me, as well as a hobby, so I take a
very different approach.

Last weekend, a friend and I discussed a project I had in mind before
I broke down and bought my UniSite. I was going to design a generalized
device programmer platform based on a "DAC per pin" architecture, much
like the UniSite. I'd use downloadable XML files (or something) to
specify programming algorithms for devices, be able to store zillions of
configs within the unit, and be able to do some minimal things (copying,
blank checks, program from a file on an SD card) without even a terminal
attached, much less a computer. It would be entirely open-source and
easily replicable.

That project got put on the permanent back burner when I bought my
UniSite, but I still think about it from time to time.

> That's why I found the Heath appealing. It sounds like that's pretty
> much what it does!

Yes. :-)

[steve shumaker]

A programmer that can handle the early stuff has been on my list for a
long time - is UniSite the specific model to look for?

Steve

[Jbensadon]

> Could the ID-4801 program any of the "odd" EPROMs that Heath used in the

> H8 or H89? Such as the 3-supply TI TMS2732, or the fusible-link PROMs
> like the 444-61?

There's a 3 supply TMS2732???  Cool.  I got derailed last summer because of the 3 rail TMS2716 in an Intertec Superbrain.
I thought the 3 railed chips ended at 2716 but apparently not.  But now I'm confused, how did they do the OE?
3 pins for 3 rails, 1 for ground, 8 for data, 12 for address, that's 24 pins.  Where's the OE pin? or did they expect you to provide your own tristate buffer?

J.

[Terry Gulczynski]

On 4/11/2014 10:07 PM, Lee Hart wrote:

> I like that it uses a Z80. I'm already thinking I could build it with a
> Z180 to get a bigger memory space, and thus allow it to program bigger
> parts. :-)
>
> Could the ID-4801 program any of the "odd" EPROMs that Heath used in the
> H8 or H89? Such as the 3-supply TI TMS2732, or the fusible-link PROMs
> like the 444-61?

It would be easy enough to replace the Z80 with a Z180 & RAM - I have a
module that does just that. The 2732 EPROM would have to be modified,
but that's the easy part. The A14 line is already available on the
personality socket, so there's no reason why it wouldn't be able to
handle 32K (27256) chips. Larger than 32K would require the A15 data
line, which isn't available on the personality socket.

Re: the 'odd' EPROMs and PROMs -- no, 'fraid not. The manual implies
that it can only program the 25xx and 27xx series chips. The
personality socket only provides +25V for the programming pulse, which
can be dropped to 21, 12, or whatever with resistors, a zener, or some
combination. There is no negative voltage available (required, I think,
for the old 3-voltage EPROMs.)


Terry

[Dave McGuire]

On 04/12/2014 12:06 PM, Terry Gulczynski wrote:
> It would be easy enough to replace the Z80 with a Z180 & RAM - I have a
> module that does just that.

Very interesting! Is this a module of your own design? Is info
available about it?

> Re: the 'odd' EPROMs and PROMs -- no, 'fraid not. The manual implies
> that it can only program the 25xx and 27xx series chips. The
> personality socket only provides +25V for the programming pulse, which
> can be dropped to 21, 12, or whatever with resistors, a zener, or some
> combination. There is no negative voltage available (required, I think,
> for the old 3-voltage EPROMs.)

Are all of the pins on the personality module allocated? I'd think
adding a negative supply wouldn't be too tough, and would be a
worthwhile modification for the ID-4801.

[Dave McGuire]

On 04/11/2014 11:23 PM, steve shumaker wrote:
> A programmer that can handle the early stuff has been on my list for a
> long time - is UniSite the specific model to look for?

It'll do back to 2708s, but not 1702s.

There are a few caveats with the UniSite. Some of them have internal
hard drives...those are the ones you want. Bruce Lane cloned the "MSM"
(Mass Storage Module) to add a hard drive (or a CF card, if memory
serves) and that's easily installed, but it requires a motherboard past
a certain rev level. I'll dig up all that info if you need it and can't
find it with a quick google.

(incidentally, my UniSite came from that very same Bruce Lane many
years ago)

There's also the matter of pin drivers. The pin drivers are on
replaceable boards, in case you fry one. Each board handles four pins,
and some machines are partially populated. A fully-configured UniSite
has 22 quad pin driver boards, to support devices with up to 88 pins.

The firmware is very expensive (thousands) to purchase from Data I/O,
but it is, erm, "around". There was a new release in the past couple of
years. It is supplied as floppy disk images that you boot the unit
from, then you can install it onto the internal hard drive, if your unit
has one. If not, you just boot from the floppies. That's a pain
because there are quite a few floppies in the full set, and you'll be
swapping them around to access setups for different devices that you
want to program.

The UniSite is the best of the "UniFamily" programmers. Other
programmers in this family are the 2900 and 3900. They are also very
good programmers (I still have my very old 2900) and much smaller, but
less capable than a UniSite. The firmware distributions are the same
across the entire UniFamily family. Schematics and service
documentation, as well as the users' manuals, for at least the UniSite
model is available on bitsavers.

[Lee Hart]

Jbensadon wrote:
> There's a 3 supply TMS2732?I'm confused, how did they do the OE?

As soon as you said this, I realized you're right! I should have said
the Texas Instruments TMS2716 that had 3 supply pins (+5v, -5v, +12v).
This was the part that Heath used in the H19 and H89.

Everyone else's 2716 had a single 5v supply. TI later came out with the
TMS2516, which was their single-supply version of the 2716.

There wasn't a 3-supply 2732; a 24-pin package doesn't have enough pins.

[Information]

We used Data I/O in Heath engineering. I don't remember the firmware being
open sourced. I do remember selling Heath a program to send Intel Hex files
to it, or perhaps converting binary files to Intel Hex, or something like
that. It may have uploaded files as well. I believe it was relatively late
in the Heath product development cycle, ie. after the H89, Z100, etc. I
sold them the software in 1985 or later.

[Dave McGuire]

The firmware has most definitely NOT been open-sourced, at least for
the UniFamily machines. Knowing how Data I/O is in their corporate
mentality, I'd be shocked to hear that ANY of their stuff has been
open-sourced.

-Dave

[Information]

Sorry, my bad. I meant that I didn't think the Heath firmware was open
sourced. I would agree that the Data I/O probably wasn't. I seemed to
remember out Data I/O cost about $10,000 in the early 1980's.

[Lee Hart]

Information wrote:
> I meant that I didn't think the Heath firmware was open sourced.

I'm sure it's not officially open-sourced; but as a practical matter, I
can't imagine that any of the Heath ghosts care about it.

Bob Crotinger sent me pdfs of the manual, and I've been perusing it.
It's a classic Heath product! All generic easy-to-get parts, big PC
board with large traces and pads for easy soldering, fully documented,
PC board layout is in the manual, etc.

I'm thinking that I can build one from scratch. Layout my own board
(with a few mods for more modern parts like the switches, LED display,
and RAM). If I do, would anyone else be interested in a board? It will
cost about the same for 1 board or 10.

The only things that aren't in the pdfs are the schematic, and the
firmware listing. Can anyone help supply them?
--
Life is basically simple. Yo do some stuff. Most fails. Some works.
You do more of what works. If it works big, others quickly copy it.
Then you do something else. The trick is the doing something else.

[steve shumaker]

I'd definitely be interested in one!


Steve

[Terry Gulczynski]

On 4/12/2014 7:27 PM, Lee Hart wrote:

> The only things that aren't in the pdfs are the schematic, and the
> firmware listing. Can anyone help supply them?

Well, I MIGHT have the schematic attached in a PDF (zipped). Haven't
done this sort of thing much, but it might work. If not, I'll be happy
to send it direct.

As for the firmware, I'll see what I can do. I'm certain I don't have
the work I did on it years ago, but I should be able to come up with
something that will at least be a good start.


Terry

[steve shumaker]

worked like a champ!


Steve

[Terry Gulczynski]

On 4/12/2014 10:17 PM, steve shumaker wrote:
> worked like a champ!
>
>
> Steve

Heh. Sometimes I really surprise myself.


Terry

[Lee Hart]

Terry Gulczynski wrote:
> Well, I MIGHT have the schematic attached in a PDF (zipped).

That's it! It came through perfectly. Thank you very much indeed. :-)

I just started looking at it. There are some interesting aspects. For
one thing, they put raw switch contacts on the INT and NMI lines, with
no debouncing. That seems rather risky. There is a comment in the manual
about "crashing" it if the LOAD button (NMI) is pressed at the wrong time.

The 74LS259 addressable latch is an unusual way to drive a display. I
wonder why Heath used that method?

I don't see how it sets the program pulse width to 50 msec. Maybe in
software? If so, it can be changed to suit newer EPROMs that generally
use much shorter times.

There are no provisions for changing the EPROM's supply voltage during
programming. Some EPROMs want you to program them with their VCC at 5.5v
or 6.5v (i.e something other than 5v). Luckily, modern 74HC parts work
fine at higher voltages, so an option could be added to change the 5v
supply voltage for the whole thing during programming.

> As for the firmware, I'll see what I can do. I'm certain I don't have
> the work I did on it years ago, but I should be able to come up with
> something that will at least be a good start.

Hmm... it's an EPROM programmer. It can program 2732 EPROMs. It *has* a
2732 EPROM in it. So, can it burn its own firmware into a new EPROM? Or
send its own firmware out the RS-232 port as an Intel hex file? :-)

[Terry Gulczynski]

On 4/12/2014 11:42 PM, Lee Hart wrote:

>
> Hmm... it's an EPROM programmer. It can program 2732 EPROMs. It *has* a
> 2732 EPROM in it. So, can it burn its own firmware into a new EPROM? Or
> send its own firmware out the RS-232 port as an Intel hex file? :-)
>

It doesn't work that way. The start address set by the keypad for any
memory access operation (such as send memory via serial, EPROM burn,
etc) maps the beginning of RAM to 0000H as the first RAM address. In
other words, the 4K of EPROM memory space is invisible to the memory
map, essentially being inaccessible to the user. (In reality, the EPROM
is mapped at 0000H-0FFFH, and the 16K of RAM begins at 1000H.)

(It just occurred to me - I wonder if I can 'wrap' the addresses around
and find the EPROM at 64K-4K = 60K = 0F000H? Never tried it; might be
interesting.)

In any case, I can use my regular programmer to read the 2732 and write
the binary file, then start the disassembly process from there.


Terry

[Lee Hart]

Lee Hart wrote:
> (It just occurred to me - I wonder if I can 'wrap' the addresses around
> and find the EPROM at 64K-4K = 60K = 0F000H? Never tried it; might be
> interesting.)

Yes, that what I was wondering about. I expected address 0000 on the
keypad is the start of RAM. But if you can enter any address from 0000
to FFFF, then the EPROM should be somewhere in that 64k space. Unless
the hardware prevents it (and I don't see anything that would). Or the
software prevents it (which is possible).

It's not a "necessary" feature, but it would be an "interesting" one.
Kind of like the RepRap machines that can make their own parts! :-)

> In any case, I can use my regular programmer to read the 2732 and write
> the binary file, then start the disassembly process from there.

Yes. If you've done it before, you can do it again. :-) But I'd hate to
put you to too much trouble. A simple copy of the existing EPROM would
get me started.

Longer term, I don't see a reason to limit the ROM space to 4k. 28-pin
EPROMs are both cheaper and more available. More space would allow more
options, like controlling it from a PC via the serial port.

[Alex - K3CIM]

Ebay item

371042895391

is starting at 9.99 $$

just went on yesterday

[Lee Hart]

Alex - K3CIM wrote:
> Ebay item 371042895391... just went on yesterday

Thanks, Alex. I just put a bid on it. The easiest way to clone it is to
have one to look at. :-)

[Dave McGuire]

On 04/14/2014 06:05 PM, Lee Hart wrote:
> Alex - K3CIM wrote:
>> Ebay item 371042895391... just went on yesterday
>
> Thanks, Alex. I just put a bid on it. The easiest way to clone it is to
> have one to look at. :-)

I just looked at it (but am not bidding) and it looks absolutely
pristine! (except for that annoying engraving toward the bottom left of
course)

[Jbensadon]

Wow, that unit looks beautiful!  Only 3 bidders up to $22 now.

PS. I'm not bidding,  it's out of my interest range at the moment.

---

Date: Mon, 14 Apr 2014 13:36:04 -0700
From: abo...@zoominternet.net
To: se...@googlegroups.com
Subject: [sebhc] Re: Heath ID-4801 EPROM programmer

--
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[Jbensadon]

Lee, Good luck on winning!  I always snipe my ebay treasures.  I go in big at the last 10 seconds.
Sometimes, there's just someone else that wants it more than me.... c'est la vie.

> Date: Mon, 14 Apr 2014 17:05:52 -0500
> From: leea...@earthlink.net
> To: se...@googlegroups.com
> Subject: Re: [sebhc] Re: Heath ID-4801 EPROM programmer

> --
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[Lee Hart]

Lee Hart wrote:
> Alex - K3CIM wrote:
>> Ebay item 371042895391... just went on yesterday
>
> Thanks, Alex. I just put a bid on it. The easiest way to clone it is to
> have one to look at. :-)

Well, it went for over $100. As usual, all the high bids were in the
last few seconds.

Meanwhile, I have entered the schematic into Orcad, which is the program
I used to layout PC boards. I found a few minor mistakes in the circuit
(places that don't agree with the PC board). There are also some
oddities, and downright errors. For example:

- Z80 address lines A0-A2 are driving 8 LS-TTL loads (too much).
- Z80 data line D0 is driving 10 LS-TTL loads (again, too much).
Can fix by using 74HC259 instead of 74LS259 for LED displays.
- More than one bypass capacitor per chip! All are 0.01uF.
But no bypass capacitor on the EPROM being programmed.
- They put an undebounced pushbutton on the Z80's NMI pin.
- The power transformer has a 30v winding, but they only used half of
it with a voltage doubler to get the 25v programming voltage.
- Complex 25v supply for the programming voltage. Everything else
used 3-terminal regulators. Why not the same for the 25v?
- Overbuilt +15v and -15v supplies with 1-amp regulators, used only
to power the RS-232 transmitter and receiver chips (which take
less than 10ma).
- In fact, the RS-232 chips should be powered at +/-12v; they have
a +/-15v absolute maximum rating.
- The 2732 4k firmware ROM is addressed from 0000-3FFF (16k).
Allows easy expansion.
- Up to 16k of RAM can be installed, addressed from 4000-7FFF.
It would be easy to expand to 32k, to program 27256 EPROMs.
- The 24-pin "personality" socket is very versatile, and can
support a wide range of parts beyond those mentioned in
the manual.
- The EPROM programming pulse length is set in software, and
(apparently) fixed at 50msec -- too long for many EPROMs.
It should be made adjustable, to suit the part being programmed.

Overall, it looks like making a "new" version of it is a worthwhile
project. For a long time, I've wanted an EPROM programmer that *I* can
control, to fix bad programming algorithms or add new parts. So I will
continue, and start laying out the PCB.

The only thing I'm missing is the firmware. Terry and Bob mentioned that
they have an ID-4801. They may be able to send a copy of its EPROM, so
that can be solved.

Right now, I'm not sure if I should build an exact clone, or play
engineer and "fix" things. Is anyone else interested in building one?
What are your thoughts?

--
Any intelligent fool can make things bigger, more complex, and more
violent. It takes a touch of genius, and a lot of courage, to move
in the opposite direction. -- Albert Einstein

[Kenneth L. Owen]

Hi Lee,

I am interested. My vote would be to stay with the general function, but to
fix the obvious 'errors?' It would be good to add a programmer to my tools.

-- ken

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[steve shumaker]

I'd be interested in building one!

Steve

[Lee Hart]

steve shumaker wrote:
> I'd be interested in building one!

Kenneth L. Owen wrote:
> I am interested.

OK; that's two (besides me). The project has begun! :-)

Terry Gulczynski is sending me his ID-4801 to play with. That will let
me see how it actually looks and works. It will also give me the
original firmware. It hasn't arrived yet, but I'm looking forward to it.

In the meantime, I entered the schematic (attached) into Orcad; the
program I use for PCB layout. In doing so, I found a few more errors
(differences between the schematic and x-ray layout printed in the Heath
manual. The corrections can be determined by looking at the actual hardware.

I've also started placing parts. It's a big board -- 7.5" x 13.5"! Since
PCBs sell by the square inch, and I can significantly lower the parts
count with newer parts, I'm wondering if I should down-size it.

- Should I keep it the same size for "nostalgia", and so it will
fit the Heath case in case someone needs a spare or upgrade?

- Or (like many of our new H8 boards), should I downsize it to
go into a smaller case? Maybe use a "filler" panel if it needs
to go into an old Heath case?

I also haven't decided how MUCH to upgrade it. There's a "slippery
slope" here. If I make too few changes, it's just an old limited
programmer of little use, instead of the fun of building a kit. If I
make too many changes, it's no longer the same, and many wouldn't enjoy
it as a retro-Heathkit.

At the moment, these are the hardware changes I see making:

1. Replace the six 74LS259 LED drivers with 74HC259. This eliminates
the heavy loading on the Z80's D0 and A0-A3 lines. It also saves
200ma of supply current.

2. Replace the 48 series resistors (one per LED segment!) with a
single 3v display regulator. Use this regulator and the inherent
output resistance of the 74HC259's to control LED current.

3. Add a 5v bypass capacitor for the EPROM being programmed.

4. Downsize the +/-15v supplies to +/12v. They are only used for
the RS-232 interface, and the chips used are only rated for 12v
(15v is the "absolute maximum" on the data sheets).

5. Add a transistor to pull down A15 (instead of 1K resistor R11).
1K isn't lower enough to get a good logic low for the LS chips
on this line.

6. Debounce the switches on the INT and NMI interrupt lines.

I see these as actual errors that should be corrected in the Heath
design. It (obviously) works without them; but they eliminate some
worst-case and reliability problems.

I also can't help "playing engineer", and trying to improve it. Here are
the hardware changes I would like to make.

7. Replace the 5 RAM chips (totalling 16k) with one 32k RAM chip.
It saves parts, lowers cost, doubles RAM, cuts power, and allows
programming bigger parts.

8. Replace the 74LS04 TTL crystal oscillator with a 74HC04 oscillator.
HC oscillators work a lot better.

9. Replace the old 741 opamp and transistor 25v regulator with an
LM317 circuit. Way less parts, better regulation, and more flexible
to get different programming voltages.

10. Rewire the halfwave voltage doubler for the 25v supply as a
fullwave bridge circuit. This reduces the transformer and
filter capacitor cost and size.

11. Move the power transformer, EMI filter, and on/off switch on-board.
I couldn't find a chassis mount transformer with the right voltages,
but I *did* find one that mounts on a PC board. It's a big board
anyway, there's lots of room, and it saves a lot of off-board
hand-wiring. A cover can be fitted to prevent shock hazards when
playing with a "naked" board.

12. Add support for programming 3-supply +12v/+5v/-5v EPROMs.
Changing the RS-232 supplies to 12v automatically provides
a 12v supply; so only a new -5v regulator would be needed.

13. Increase the size of the firmware EPROM (from 4k to 8k)?
Allows room for the program to grow.

14. Add a RAM just for the program (say, 8k). The firmware manages
to work without RAM (all RAM is used for EPROM burn memory),
but it would be *far* easier to write code with RAM for stacks
and variables. RAM would also allow Z80 programs to be loaded
and run (for testing, new features, etc.)

15. Add support for newer (larger) EPROMs and/or other chips.
The big question is how far to go with this. Adding a bigger
RAM and EPROM socket is easy, so this is mainly a software
issue. Someone has to find the programming algorithms and
add support for them. There are already cheap programmers for
newer chips, so there may be no incentive to do this (except
to have an open-source upgradeable and fixable programmer).

16. Serial port: There are several possibilities here. Use a MAX232
to eliminate the discrete +/-12v supplies. Add a socket for an
FT-232 USB-to-serial converter, so it could be connected to PCs
with only USB ports.

Software:

The present firmware is fairly limited. For example, it only loads and
saves hex files for EPROM programming. All other operations are
controlled by the programmer's keypad. It would be nice to be able to
*control* all programming functions from a PC.

A fixed 50msec programming pulse is used. But this can be made software
selectable to just about anything. Many "smart" EPROM programming
algorithms do things like apply short pulses until the EPROM verifies,
then "hit" it with a 3x longer programming pulse to insure it is
reliable. This lets you program good parts much faster, and programs
weak parts that need a bit more.

Keep in mind that this thing is in reality a general-purpose Z80
"trainer" with RAM, ROM, keypad, hex LED display, serial port, and 3
parallel ports (that just happen to be used for EPROM programming).
There are a lot of other things that can be done with this hardware!

Am I getting too "techie" with this? Should I take these discussions
off-list?

--
If we knew what we were doing, it wouldn't be called research, would it?

[Norberto]

Very nice and I agree with your assessment. It will be nice to provide a list of supported ROM's before any board layout is started.

Sent from my Verizon Wireless 4G LTE DROID

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[Bill Reilly]

This sounds intriguing, as I have an ID-4801 shipping to me right now. I'm wondering if there is any way to abstract the physical personality modules into perhaps a software/firmware library on board. Perhaps a table of EPROM models, then a description of pin connections, voltages, and timings, stored locally in persistent memory (flash or SD-Card?) This takes the project squarely out of the physical wiring/Personality module space, and may depart too much from the Heathkit retro feel.

In software, through the keypad or via the serial interface, perhaps several administrative commands could be used to Load EPROM Definition; Save EPROM Definition; and Define EPROM settings.

If the definition covered every pin, including power, ground, etc, and electronic switches were used to route the appropriate signals to the identified pins, the community could contribute almost any programmable device. You would only have to load the ones you wanted.

Just dreaming.

Bill

[Lee Hart]

From: Bill Reilly <qwi...@gmail.com>

>This sounds intriguing, as I have an ID-4801 shipping to me right now. I'm wondering if there is any way to abstract the physical personality modules into perhaps a software/firmware library on board. Perhaps a table of EPROM models, then a description of pin connections, voltages, and timings, stored locally in persistent memory (flash or SD-Card?) This takes the project squarely out of the physical wiring/Personality module space, and may depart too much from the Heathkit retro feel.

The ID-4801 personality modules are just an IC pin header that plugs into a mating IC socket. They have jumpers to connect the /CS, /OE, and VPP programming voltages to the right pins of the EPROM you want to program. No hardware, and no software in the programmer itself. Dirt simple, and adaptable to *any* programmable device.

A modern programmer replaces the physical jumpers with a set of digital switches. It will also have a much larger memory to hold the configuration tables needed to cover the hundreds of different EPROMs. It's nice that it's programmed for you. But virtually none of these programmers are "open source" -- you can't inspect the algorithms to see if they are actually doing what the manufacturer wants (many don't; they take short cuts). You can't add new parts, when something new comes out. You can't modify the tables if a manufacturer's parts needs a slightly different programming algorithm.

Me; I'm an occasional EPROM programmer. I don't need a device that's instantly programmable for hundreds of parts I'll never use. But sometimes I run across old parts that aren't covered. I don't mind wiring a header to program these parts myself.

For example, Heath used a lot of 3-supply EPROMs. Almost no modern "universal everything" programmer can program them. But the ID-4801 can, if you make a configuration header for it. :-)


--
Excellence does not require perfection. -- Henry James
--
Lee A. Hart http://www.sunrise-ev.com

[Glenn Roberts]

There was a small amount of "hardware" in some of the personality modules, basically resistors and Zener diodes, I presume to get the programming voltages right? only a few of them required these; most were just jumpers as Lee says. I have the illustration book (in storage) with the wiring diagrams for the popular EPROMS of the time, including (as someone here pointed out) an ability to use the ID-4801 for live in-circuit EPROM emulation. Pretty cool stuff.

- glenn

> -----Original Message-----
> From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of
> Lee Hart

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> 0wamui-nigel.atl.sa.earthlink.net.

[Lee Hart]

From: Glenn Roberts <glenn.f...@gmail.com>

>There was a small amount of "hardware" in some of the personality modules, basically resistors and Zener diodes, I presume to get the programming voltages right? only a few of them required these; most were just jumpers as Lee says.

Right-0! The ID-4801 has an adjustable voltage regulator for the programming voltage. Resistors are included for common programming voltages (25v, 21v, etc.) so for them the personality modules are just wire jumpers. For other voltages, you install resistors in the personality module. I did this recently to program some 27C16BQ EPROMs. Unlike standard 2716's, these needed VPP=12.5v.

Including (as someone here pointed out) an ability to use the ID-4801 for live in-circuit EPROM emulation.

In fact, I'm using that feature right now. Josh Bensadon and I are developing the software for my Altaid 8080 <http://sunrise-ev.com/8080.htm>. He has it running CP/M. Imagine an H8 you can put in your pocket. :-)

[G. Beat]

I see some more Heathkit ID-4801 EPROM programmers have appeared on eBay,

at reasonable (and unreasonable) prices.

I also note that DataPro is offering the IDA-4801-1 Kit Optional Personality Adapters (eBay) for $35.00

greg

==
Lee wrote:

Hi Gang,

I happened to notice a Heath ID-4801 EPROM programmer on eBay. I had
never run across this product before. Naturally, the seller doesn't have
the manual or any docs, and has no idea if it works. (That doesn't stop
him from asking Top Dollar for it anyway.)

But I'm curious. Are any of you familiar with it? What's it program? is
a manual available? The attractive thing about a Heath EPROM programmer
is that it should be "open source" enough to see how it works, so I
could add newer chips to it.

PS: My main EPROM programmer right now is a Valley Data Sciences
VDS-150+, which is an accessory for the H89! :-) It is in a cabinet
styled like the H89. The EPROM socket area is where the keyboard of an
H89 is. An H77 drive enclose can sit on top of it, so the "stack" of the
programmer and H77 match the profile of the H89. It connects to the H89
with an interface card that plugs into one of the I/O slots.

It's a nice programmer, but of course they are out of business, and only
supplied "closed source" software and hardware. No schematics, and no
way to upgrade it. It can't program any parts newer than about 1985.

--
Ring the bells that still can ring
Forget your perfect offering
There is a crack in everything
That's how the light gets in.
        -- Leonard Cohen, from "Anthem"

[Glenn Roberts]

You can also pick up a Heath EPROM eraser…

 

https://www.ebay.com/itm/Vintage-Heathkit-Heath-EPROM-Eraser-4803-Tested-and-Working/124012121599

 

 

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[Lee Hart]

G. Beat wrote:
> I see some more Heathkit ID-4801 EPROM programmers have appeared on eBay,
> at reasonable (and unreasonable) prices.
>
> I also note that DataPro is offering the IDA-4801-1 Kit Optional
> Personality Adapters (eBay) for $35.00
>
> greg

Ooh, speaking of the ghost of Christmas past; that's an old post of
mine! :-)

I now have an ID-4801. It works, and I have all the docs for it and use
it occasionally. It's a little inconvenient, because you have to wire up
a little header as a "programming adapter" -- one for each part you want
to program. But it's very versatile; if you have the specs as to what
programming pulse and voltage a part needs, you can get it.

It has one useful trick I've been using to debug/develop other gadgets.
It can act as a EPROM emulator. You plug it into a "target" system in
place of its EPROM, and the ID-4801 works in place of its EPROM. You can
enter bytes into this EPROM from the keypad, or via the serial port, and
then execute them on the target system. Very useful for bringing up a
"new baby". :-)

Lee

--
ICEs have the same problem as lightbulbs. Why innovate and make
better ones when the current ones burn out often enough to keep
you in business? -- Hunter Cressall
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

[Steven Hirsch]

On 12/16/19 9:01 PM, Glenn Roberts wrote:
> You can also pick up a Heath EPROM eraser…
>

I built one of those about 30 years ago and still use it.

[Lee Hart]

Steven Hirsch wrote:
>> You can also pick up a Heath EPROM eraser…
> I built one of those about 30 years ago and still use it.

Me too. Nice because they are long enough to erase 10-12 EPROMs at a time.

But it needs a timer so you don't erase them to death. I added a
60-minute Intermatic spring-wound timer (like they use for bathroom fans
or outdoor lights) to turn it off automatically. 2-30 minutes is enough
for most EPROMs.

Heath built good stuff!