RomWBW support for Z80-Retro by john winans

[Derek Cooper]

Hi everybody (in particular Wayne Warthen)

I was wondering if the z80-Retro has support in RomWBW, I seem to recall a message that mentioned this some time ago.

In particular, I noticed that John has developed an SD-CARD software interface for his board. It's documented by him on his github site etc. Would it be possible to add something like it to RomWBW.

I know it would be really slow, but even at 150kps it's still the same as old disk drives managed anyway. And it's not about speed.

Derek

[Wayne Warthen]

On Saturday, August 19, 2023 at 8:48:06 AM UTC-7 derek.coo...@gmail.com wrote:

I was wondering if the z80-Retro has support in RomWBW, I seem to recall a message that mentioned this some time ago.

Yes, there is support for this platform, but it is only available in the Development Snapshot at this time.  It was donated by Alan Cox.  You will find Z80RETRO_std.rom as a prebuilt ROM image in the current Development Snapshot builds.

In particular, I noticed that John has developed an SD-CARD software interface for his board. It's documented by him on his github site etc. Would it be possible to add something like it to RomWBW.

Alan included Z80-Retro SD Card support.  It is enabled by default.  I don't have the Z80-Retro hardware, but it should work.

Thanks,

Wayne 

[Alan Cox]

Different Z80 retro. Probably hard to do Romwbw well for Johns as it copies the u banked 64K ROM to RAM at boot and then the ROM is paged out for good

--
You received this message because you are subscribed to the Google Groups "retro-comp" group.
To unsubscribe from this group and stop receiving emails from it, send an email to retro-comp+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/retro-comp/740eccf6-d82c-4875-ba44-eb1a4701a9e1n%40googlegroups.com.

[Wayne Warthen]

On Saturday, August 19, 2023 at 3:21:15 PM UTC-7 Alan Cox wrote:

Different Z80 retro. Probably hard to do Romwbw well for Johns as it copies the u banked 64K ROM to RAM at boot and then the ROM is paged out for good

Thanks Alan.  I didn't realize there were multiple Z80 Retro projects.  So, the original message you saw about Z80 Retro support refers to Peter Wilson's Z80-Retro (https://github.com/peterw8102/Z80-Retro) which is indeed supported by RomWBW.  The other project (that Derek refers to) is John Winans' Z80 Retro! (https://github.com/Z80-Retro) which is not supported by RomWBW.

As Alan mentioned, John Winans' Z80 Retro! would be sub-optimal under RomWBW for multiple reasons that I'm not going to try and enumerate here.

Sorry for my earlier confusion about this.

Thanks,

Wayne

[Alan Cox]

> Thanks Alan. I didn't realize there were multiple Z80 Retro projects. So, the original message you saw about Z80 Retro support refers to Peter Wilson's Z80-Retro (https://github.com/peterw8102/Z80-Retro) which is indeed supported by RomWBW. The other project (that Derek refers to) is John Winans' Z80 Retro! (https://github.com/Z80-Retro) which is not supported by RomWBW.

There are about five I can think of. It's a very oversubscribed name.
This is why Fuzix and the emulator kit all refer to John's by his
project number (2063).

Alan

[eprive]

There are MANY, a whole lot of retro kits and designs that have a SD interface that emulates the good old mechanical drives ( HDD and FDD ). I built one from the well known italian designer (aka Just4Fun) in year 2020. A single board computer with only 5 ICs that does almost everything that the first generation of modular CP/M machines could do in an enclosure that weighed over 10 kg.

It is a popular kit project, and I took it as the base for an enhanced (Multi Boot Computer) since it can boot into CP/M 3.0, QP/M, UCSD Pascal, Collapse OS, BASIC and Forth too.
I figured it could be made with even less components, but MORE features. An analogue input with potentiometer and a beeper are now on the same sized board ( 100 x 100 mm. ), and accept the same plugin modules ( SD card adapter, DS3231 real time clock, and an FTDI USB to TTL RS232 ). And it has a GPIO chip that provides 8 parallel I/O, and is expandable with more external I2C peripherals including the more expensive MCP23017.
This updated design is also obtainable as a kit or assmbled and tested. And not difficult to find if you're familiar with eBay, Github, or Facebook.

Willem

Op zaterdag 19 augustus 2023 om 17:48:06 UTC+2 schreef derek.coo...@gmail.com:

[Alan Cox]

> In particular, I noticed that John has developed an SD-CARD software interface for his board. It's documented by him on his github site etc. Would it be possible to add something like it to RomWBW.

I meant to reply to this bit too. There is bitbamg SD support in
ROMWBW and I extended it to cover the other Z80Retro, SC129 and the
Z80 PIO adapters - which was fairly trivial as all the work is done in
the core codel. The Fuzix code is about 19KBytes/second raw throughput
the ROMWBW a shade slower, so perfectly adequate for CP/M and
reasonably acceptable for Fuzix providing it's not swap and you've got
a reasonable amount of RAM. Not so great at 4MHz on a more classic
speed machine but still acceptable. That said if you have a PIO it's
sufficient to drive a CF adapter instead akin to the PPIDE.

I think you can get a Simple80 style design down to 4 chips including
I/O and 512K banking providing you use a 2681 derived UART with GPIO
lines rather than the SIO. The UART change gives you the GPIO lines
you need for the SD, and a timer tick. With a few diodes probably also
I2C.

Alan

[Tadeusz Pycio]

Great idea!  That it also didn't occur to me before.... I already know what I'm going to do with my XR88C681 module. :-)

[Bill Shen]

Redesign Simple80 with KIO maybe interesting and keep it cheap like the original intent.

  Bill

PS, Simple80 kit is still $7 but shipping is $9.  123 kits sold so far

[PauldB]

I'm guilty for 3 of the Simple80 kits. Great fun :)

Perhaps a matter of interest, two of the boards run reliably @ 2.90V (zexdoc, pip w/verify, xmodem, asciiart, etc). Couldn't test the third board 'cause I added the voltage supervisor to it ;)

These are the chips I got from the eBay seller:

Z84C0010PEC
Z0844104PSC  <-- gets slightly warm; would confirm NMOS - works at 2.90V !?
Winbond W27C512-45
Toshiba TC551001BPL-85L
74HC00N
74HC32P

Plus used:

7.3728 MHz Osc
Cisco 256 MB CF card
CP2102 USB-to-TTL adapter
Simple80 Monitor v0.81 5/30/23

There is obviously quite some interest in Simple80. I'd love to see how you can  improve it while still keeping it through-hole and cheap ;)

Thanks,
Paul

[Bill Shen]

A simple80 fan!  Wow, 2.9V operation.  I have consistently got 3.3-3.4V at 7.37Mhz.  At 5V it should run at 14.7Mhz.  29.5mhz is sometimes possible with fast RAM.  KIO is a $3-4 part in PLCC package.  I consider it a through-hole component when used with a through-hole PLCC socket.  KIO has discrete IO to bit-bang SD card and bank switch 512K RAM, but running RomWBW with 64K-size banks may be quite difficult.

  Bill

[Alan Cox]

> A simple80 fan! Wow, 2.9V operation. I have consistently got 3.3-3.4V at 7.37Mhz. At 5V it should run at 14.7Mhz. 29.5mhz is sometimes possible with fast RAM. KIO is a $3-4 part in PLCC package. I consider it a through-hole component when used with a through-hole PLCC socket. KIO has discrete IO to bit-bang SD card and bank switch 512K RAM, but running RomWBW with 64K-size banks may be quite difficult.
> Bill

I think Fuzix is still the only OS crazy enough to be able to use
multiple 64K banks properly. CP/M you can still use it as a ramdisc
but not much else. 32K/32K with the limit that you can select only
between half the memory in the low and half in the high is also not
hard (just a 2 way 4bit demux - as the 8085 MMU does). I think with a
KIO or 2681 derived setup you'd still be less parts than the CF
adapter. You can also stay 8bit CF I think in the KIO case as you need
15 pins for 8bit CF on the PIO (plus some resistors), and you've got
the PIA pins to provide the memory banking. The PIA starts as input so
just needs pullups.

You'd need the Z80, the KIO, ROM, RAM, a mux and an inverter I think

If you stuck to 128K RAM / 128K ROM so you've got the extra CS then
you'd just need the mux and could put any RAM/ROM 32K into low or high
? 5 chips including CF or SD


Alan

[Derek Cooper]

ok i give in, a pointer please.

Where do I set the port, MISO, CLK and MOSI bit mask in the config file. I plan on building a prototype SD-CARD adapter, maybe based on one of the existing ones. But I just don't get the complicated setup in the config files.

Thanks

Derek

[Wayne Warthen]

Hi Derek,

On Wednesday, August 23, 2023 at 3:30:46 AM UTC-7 derek.coo...@gmail.com wrote:

Where do I set the port, MISO, CLK and MOSI bit mask in the config file. I plan on building a prototype SD-CARD adapter, maybe based on one of the existing ones. But I just don't get the complicated setup in the config files.

To answer your question, it is a tad more complicated than settings in the config file.  The SD Card driver (sd.asm) uses a SDMODE setting to specify the device configuration.  Near the top of the sd.asm file, you will see that the  SDMODE setting is used in conditional compilation to set a bunch of variables when building the driver.  To create a new interface variant, you would create a new SDMODE value, then add a new section for it at the top of sd.asm.  It is messy because there are a wide variety of SD Card interface designs.  I can help you with the driver changes when you get to that point.

With that said, I am unclear what platform you are targeting.  Neither Z80-Retro (John's) nor Simple80 will run RomWBW.

Thanks,

Wayne

[Derek Cooper]

Thanks Wayne,

It will be a week or two as they say. I'm going for an RCBUS type card for the SC720 or SC700 series.

Derek

[Wayne Warthen]

On Thursday, August 24, 2023 at 9:40:19 AM UTC-7 derek.coo...@gmail.com wrote:

It will be a week or two as they say. I'm going for an RCBUS type card for the SC720 or SC700 series.

OK, that is certainly a platform with RomWBW support, so no issue there.  I will happily help with driver config when you are ready.

At the top of the driver source file (sd.asm) is a table that shows all of the current interfaces supported.  You don't need to match one of those circuits, but it may be useful as a way to find useful examples.

Thanks,

Wayne