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Alan Cox
Mar 30, 2020, 12:57:37 PM3/30/20
to retro-comp
The 68008 needs some fixes (I screwed up the RD/WR decoding), the 80C188 needs a new board because it turns out Intel don't use the standard PLCC68 pin numbering scheme (rude words..)
However the 1802 is now cycling light patterns on the SC129 debug card.
Currently it's just running with an SC129 and a 32K/32K memory card. The claims about the CMOS 1802 power consumption also appear to be true. The lights cycle happily on for about 5-10 seconds after I turn the power adapter off at the wall.
Alan Cox
Mar 30, 2020, 12:58:04 PM3/30/20
to retro-comp
Rob Gray
Mar 30, 2020, 5:24:32 PM3/30/20
to retro-comp
Does the 1802 have any advantages over the Z80 or 6502? Or like me, do you just like a trip down memory lane to play with stuff you did back in the day?
Alan Cox
Mar 30, 2020, 6:59:44 PM3/30/20
to retro-comp
On Monday, 30 March 2020 22:24:32 UTC+1, Rob Gray wrote:
Does the 1802 have any advantages over the Z80 or 6502? Or like me, do you just like a trip down memory lane to play with stuff you did back in the day?
The 1802 was a very early processor and one of the first low power
ones. It's got some useful oddities like a DMA interface and a very
early graphics chip but it basically survived not because it was good
but because it was incredibly low power and because it was made to
military and even space grades, including silicon on sapphire chips
fabbed in an agreement with the US government labs.
It has very few redeeming features: it's slow, it's weird and if you
are used to conventional 8bit processor programming an interesting
experience because it is based around a co-routine model not
call/return. Instead of call/return you can make any one of the 16
index registers the program counter.
This is my first 1802 experience it just looked like fun and the chips
are easy to get (except the video chip but that's been cloned as a
tiny little PCB now). So far I've produced an assembler, an emulator,
a CPU board and a hello world program.
I should probably try and port IDIOT (the monitor) and BASIC I guess.
ones. It's got some useful oddities like a DMA interface and a very
early graphics chip but it basically survived not because it was good
but because it was incredibly low power and because it was made to
military and even space grades, including silicon on sapphire chips
fabbed in an agreement with the US government labs.
It has very few redeeming features: it's slow, it's weird and if you
are used to conventional 8bit processor programming an interesting
experience because it is based around a co-routine model not
call/return. Instead of call/return you can make any one of the 16
index registers the program counter.
This is my first 1802 experience it just looked like fun and the chips
are easy to get (except the video chip but that's been cloned as a
tiny little PCB now). So far I've produced an assembler, an emulator,
a CPU board and a hello world program.
I should probably try and port IDIOT (the monitor) and BASIC I guess.
Alan
TonyD
Mar 31, 2020, 5:58:14 AM3/31/20
to retro-comp
Alan, where did you get the 1802 chips from?
Tony
Tony
Jose Maria
Mar 31, 2020, 6:27:39 AM3/31/20
to retro...@googlegroups.com
Hello
Search for CDP1802ACE in Aliexpress...
For example: https://aliexpress.com/item/33030337643.html
Best,
El 31/3/20 a las 11:58, 'TonyD' via
retro-comp escribió:
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Alan Cox
Mar 31, 2020, 6:46:23 AM3/31/20
to retro-comp
Got mine off ebay. Seemed to be plenty of sources for them. 1805 should work too.
The 1861 is much harder to find but there is a modern clone on a dip sized PCB. You also need a very specific oscillator frequency if you want to use it.
Stephen Buck
Mar 31, 2020, 1:16:02 PM3/31/20
to Alan Cox, retro-comp
Can't wait to try one of these boards! There's a lot happening in the 1802 world these days!
On Tue, Mar 31, 2020 at 4:46 AM Alan Cox <etched...@gmail.com> wrote:
Got mine off ebay. Seemed to be plenty of sources for them. 1805 should work too.
The 1861 is much harder to find but there is a modern clone on a dip sized PCB. You also need a very specific oscillator frequency if you want to use it.
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Alan Cox
Mar 31, 2020, 2:25:57 PM3/31/20
to retro-comp
On Tuesday, 31 March 2020 18:16:02 UTC+1, Stephen Buck wrote:
Can't wait to try one of these boards! There's a lot happening in the 1802 world these days!
I'd offer to post you one except for the small matter of not being able to escape the house right now.
I now have it loading a program off the CF card and running it. I guess that means that with sufficient round tuits and a paged RAM/ROM or 512K RAM/ROM card you could run ElfOS on it.
Alan
Mark T
Mar 31, 2020, 4:50:23 PM3/31/20
to retro-comp
The method of calling and returning from subroutines looks similar to that used with ins8060 sc/mp, but with more index registers available. Sc/mp only has three.
Maybe the same trick works on 1802, at the end of the subroutine after the changing pc register you put a jump back to the start of the subroutine. Then you don’t need to keep setting the address for each subsequent call.
Just resurrected my MK14, memory examine and modify was behaving strange, jumping addresses out of sequence. Suspect I damaged the ram due to bus contention caused by dry joints in the decoding. Ram replaced and now working as expected so lucky the proms were ok. Now back to trying to remember which corner of each key gives a single entry often enough to enter a program. Still have to refit the 8154 and hope thats still ok, and if possible find some old matching RS component IC sockets to finally expand the memory to a massive 640 bytes.
Mark
Maybe the same trick works on 1802, at the end of the subroutine after the changing pc register you put a jump back to the start of the subroutine. Then you don’t need to keep setting the address for each subsequent call.
Just resurrected my MK14, memory examine and modify was behaving strange, jumping addresses out of sequence. Suspect I damaged the ram due to bus contention caused by dry joints in the decoding. Ram replaced and now working as expected so lucky the proms were ok. Now back to trying to remember which corner of each key gives a single entry often enough to enter a program. Still have to refit the 8154 and hope thats still ok, and if possible find some old matching RS component IC sockets to finally expand the memory to a massive 640 bytes.
Mark
Colin MacArthur
Mar 31, 2020, 5:13:32 PM3/31/20
to retro-comp
Alan, would you please post the Gerber's.
I get an ERROR when I try to open the one from hackaday...
THX
CM
FYI
I have a tube full of 1802 from my youth when I build a few COSMAC...
I dug them out when Bill started doing his G8PP as I hoped he would do an 1802 version...
Interocitor Steve
Apr 2, 2020, 1:12:47 AM4/2/20
to retro-comp
On Monday, March 30, 2020 at 5:24:32 PM UTC-4, Rob Gray wrote:
Does the 1802 have any advantages over the Z80 or 6502? Or like me, do you just like a trip down memory lane to play with stuff you did back in the day?
Memory lane Rob?
Turn back the hands of time. I wrote machine code on a Netronics(sic) Elf II. It was my introduction to microprocessors. I thought it was a very very slick chip. Sixteen registers all the same, anyone could be the stack pointer or the program counter. Regarding interrupts, I seem to remember it had very low overhead and subroutine calls and returns were just a few bytes long. In order to leverage the versatility of the register set, you had to designate registers for purposes - PC, stack pointer, and one other use I cannot remember - maybe the return address? There was one instruction which set/switched the PC counter and stack pointer. There was a recommended call and return procedure. Slicker than snot on a door knob. I seem to remember using register A for passing values.
The video was primitive but I managed a character set and repeated a few lines to give the letters a bit of charm. The characters were 3 x 5, but I repeated the second and fourth lines three times. The letter E - and it looked about this big on the screen, too.
And... because I could only fit 8 characters on the screen, I had the lines scroll like a marquee across the screen. I remember adjusting video line start addresses during vertical retrace. The video generator was just one chip and poked the DMA channel for bits as it needed them while tracing a horizontal line on the screen. Non-video processing was done during retraces.
And I made some maze games.
And I burned EEPROMs.
And, the programs were stored on paper tape.
Sheeze, I'm a dinosaur.
But the coolest things was this. This was the first popular CMOS CPU. CMOS is noise immune. When I hooked a primitive ADC up to the cpu board, I thought my scope was going on the fritz. I just couldn't get a clean display w/out 60Hz noise. The scope appeared to have an ungrounded probe. I finally discovered that the 7812(?) regulator on the CPU board was shot -- shot as in power IN was shorted to power OUT, and the regulator had an open ground. So, as it turned out, my scope probes and scope were fine, and the computer board was getting unfiltered and unregulated power from a bridge rectifier - just 120Hz camel humps all the way.
I thought this could not be true. But, I replaced the regulator and powered the system back up. All worked just as before, except this time there was 12 volts on the positive rail instead of AC ripple. I took me about two hours to figure this out.
The RCA manual was very good at getting me started. It also extolled the virtues of CMOS as a low power and noise immune technology. I certainly believed that after my experience. RCA marketed the 1802 to automotive applications because if wasn't fazed by ignition systems.
Interesting note, Alan, about military uses. I worked on radiation hardened processors for space platforms and they used CMOS parts with LARGE gates to avoid single-event-upsets. Actually, IBM made the parts on site at Manassas Virginia. I got to look into the silicon fabrication labs, but never got a walk inside.
The rest is history I suppose. IBM got out of military programs. NTSC video is gone. Eight characters across a screen is laughable. But it was a time of great learning -when you could flip bits and see the results. I commend the1802 and a hex keypad to anyone who wants to understand.
The video was primitive but I managed a character set and repeated a few lines to give the letters a bit of charm. The characters were 3 x 5, but I repeated the second and fourth lines three times. The letter E - and it looked about this big on the screen, too.
And... because I could only fit 8 characters on the screen, I had the lines scroll like a marquee across the screen. I remember adjusting video line start addresses during vertical retrace. The video generator was just one chip and poked the DMA channel for bits as it needed them while tracing a horizontal line on the screen. Non-video processing was done during retraces.
And I made some maze games.
And I burned EEPROMs.
And, the programs were stored on paper tape.
Sheeze, I'm a dinosaur.
But the coolest things was this. This was the first popular CMOS CPU. CMOS is noise immune. When I hooked a primitive ADC up to the cpu board, I thought my scope was going on the fritz. I just couldn't get a clean display w/out 60Hz noise. The scope appeared to have an ungrounded probe. I finally discovered that the 7812(?) regulator on the CPU board was shot -- shot as in power IN was shorted to power OUT, and the regulator had an open ground. So, as it turned out, my scope probes and scope were fine, and the computer board was getting unfiltered and unregulated power from a bridge rectifier - just 120Hz camel humps all the way.
I thought this could not be true. But, I replaced the regulator and powered the system back up. All worked just as before, except this time there was 12 volts on the positive rail instead of AC ripple. I took me about two hours to figure this out.
The RCA manual was very good at getting me started. It also extolled the virtues of CMOS as a low power and noise immune technology. I certainly believed that after my experience. RCA marketed the 1802 to automotive applications because if wasn't fazed by ignition systems.
Interesting note, Alan, about military uses. I worked on radiation hardened processors for space platforms and they used CMOS parts with LARGE gates to avoid single-event-upsets. Actually, IBM made the parts on site at Manassas Virginia. I got to look into the silicon fabrication labs, but never got a walk inside.
The rest is history I suppose. IBM got out of military programs. NTSC video is gone. Eight characters across a screen is laughable. But it was a time of great learning -when you could flip bits and see the results. I commend the1802 and a hex keypad to anyone who wants to understand.
Probably more than you wanted to know, Rob?
This is a great forum =Steve.
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