Found this...



The 9958 is a weird DIP packaging so maybe the 9918. The Retrobrew Computers N8 Home Computer uses it. Looks like the VDP, RAM, three buffer chips and some decoding.

Rich

--
Rich Cini




?On 7/26/20, 2:44 PM, "Lee Hart" <[email protected] on behalf of leeahart@...> wrote:

Richard Cini wrote:
> Lee -- I know decidedly unvintage, but you can use an ATMEGA88 as a composite
> color video chip...

Of course I can. *Any* modern micro can generate video. For that matter,
there are many little boards I can buy that do it all for me. Nothing to
design, no software to write. But what's the fun in that? :-)

I guess it's like doing a jigsaw puzzle. You could just buy the finished
picture; no assembly required. But the fun is in the assembly.

And for me, the fun is in the design. Not the modern "beat every problem
to death with a sledgehammer" approach, but rather the Dr. Dobbs
"running light without overbyte" philosophy.

So, I set a hard goal for myself, and then see if I can achieve it. How
simple can it be and still do the job?

For inspiration, I look back on things like the Heathkit H19 terminal
(1979), Sinclair ZX80 (1980), and Voja Antonic's Galaksija computers
(1982). They all used a Z80 with minimal vintage hardware to produce a
terminal with keyboard and video. There are also Don Lancaster's "cheap
video" tricks, which mostly centered on the 6502.

I have several designs that *almost* fit on an Altoids size card. But
none have quite given me that "aha" moment yet.

Lee Hart
--
"We do these things not because they are easy; but because they are
hard." -- President Jack Kennedy, on the Apollo moon mission
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

Hi Lee,

Do you have a datasheet or part number for the replacement LED display?? I would like to read about it.

Thanks, Steve

Lee, I probably caused the availability problem with the original display you were using.? I found that to be a really neat display, so I designed it into a specialized low-volume product I produce for a client, and to ensure enough stock, I bought all they had (about 1,100 of them).? I figure that once that supply is exhausted, the product will have made enough profit to justify re-spinning the board for a new display.? I did the same with the user-interface buttons I'm using, too.

This may not seem like a particularly sound practice for a real commercial product, but it's worked out well for me; if I guess right about the projected quantity, it can save quite a lot of money.? There's certainly plenty of precedent: Many of the 70s- and 80s-era home computer kits used this model, as did (and still do) many of the "boutique" audio and musical instrument manufacturers.
~~

Mark Moulding

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Richard Cini wrote:

Lee -- I know decidedly unvintage, but you can use an ATMEGA88 as a composite
color video chip...

Of course I can. *Any* modern micro can generate video. For that matter, there are many little boards I can buy that do it all for me. Nothing to design, no software to write. But what's the fun in that? :-)

I guess it's like doing a jigsaw puzzle. You could just buy the finished picture; no assembly required. But the fun is in the assembly.

And for me, the fun is in the design. Not the modern "beat every problem to death with a sledgehammer" approach, but rather the Dr. Dobbs "running light without overbyte" philosophy.

So, I set a hard goal for myself, and then see if I can achieve it. How simple can it be and still do the job?

For inspiration, I look back on things like the Heathkit H19 terminal (1979), Sinclair ZX80 (1980), and Voja Antonic's Galaksija computers (1982). They all used a Z80 with minimal vintage hardware to produce a terminal with keyboard and video. There are also Don Lancaster's "cheap video" tricks, which mostly centered on the 6502.

I have several designs that *almost* fit on an Altoids size card. But none have quite given me that "aha" moment yet.

Lee Hart
--
"We do these things not because they are easy; but because they are hard." -- President Jack Kennedy, on the Apollo moon mission
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

Lee --

I know decidedly unvintage, but you can use an ATMEGA88 as a composite color video chip. I use it on my 6502 SBC. It needs an oscillator (16MHz), two resistors, the chip and an RCA jack (or flying leads to an RCA jack). There are VGA solutions too, using for example the Propeller chip. Take a look at the board from S100Computers. Obviously you can cut a lot out of the design (like decoding and port selection, the LED displays, etc.).





Rich

--
Rich Cini




?On 7/26/20, 1:31 PM, "Lee Hart" <[email protected] on behalf of leeahart@...> wrote:

ajparent1/kb1gmx wrote:
> Thump thump.. testing 123 test test...
> IS there any life or is it dead?

Hi Allison,

It's alive; just sleepy. Too many distractions, I guess. Let me see...
what have I been doing with the Z80MC lately?

1. The 7-digit LED display has become hard to get. I found a
replacement, with green 7-segment LEDs. It's also a surplus part, but I
got enough to last a while; so I can keep producing kits for the
forseeable future. Physically, it has wire leads instead of pins (they
have to be bent slightly to fit the holes in the PCB) and lacks the
"steps" in the corners of the old red LED display. That's it in the
picture of the Front Panel card on my web page
<>.

2. I changed the LED-photoresisor optocoupler (used to control the piezo
speaker) to a standard LED-phototransistor part. It added a resistor
(and I always fight to minimize parts), but it's a standard part and so
easier to get.

3. I made a few improvements to the CPU board:

- I flipped the 5v regulator upside down, so its metal tab faces
*away* from the PCB; this provides better cooling.

- It also made room to add a 6-pin power/serial header (same as on the
Front Panel card). Use this header with a USB-serial cable run the CPU
board "barefoot" (without any other cards). The plan is to sell the CPU
board by itself for half the price, for any little Z-duino projects you
may have.

- I added jumper options to put BUSAK and BUSRQ on the bus in case
they're needed. but there's an error in the silkscreen; the HALT and
BUSAK are swapped. I'll fit it in the next batch of PCBs.

4. I've been "scheming" for a way to add a video/keyboard "terminal"
card. I have several designs, none of which I'm entirely happy with. We
can discuss them if anyone's interested.

5. A customer found a bug in the Dunfield BASIC; it can crash when
handling strings. I haven't had time to track this one down yet. Anybody?

What have YOU been doing with the Z80MC?

Lee Hart

--
If happiness is on your mind, here's a daily list to find:
- something to do
- something to look forward to
- someone to love
- someone to take good care of
- and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

ajparent1/kb1gmx wrote:

Thump thump.. testing 123 test test...
IS there any life or is it dead?

Hi Allison,

It's alive; just sleepy. Too many distractions, I guess. Let me see... what have I been doing with the Z80MC lately?

1. The 7-digit LED display has become hard to get. I found a replacement, with green 7-segment LEDs. It's also a surplus part, but I got enough to last a while; so I can keep producing kits for the forseeable future. Physically, it has wire leads instead of pins (they have to be bent slightly to fit the holes in the PCB) and lacks the "steps" in the corners of the old red LED display. That's it in the picture of the Front Panel card on my web page <>.

2. I changed the LED-photoresisor optocoupler (used to control the piezo speaker) to a standard LED-phototransistor part. It added a resistor (and I always fight to minimize parts), but it's a standard part and so easier to get.

3. I made a few improvements to the CPU board:

- I flipped the 5v regulator upside down, so its metal tab faces *away* from the PCB; this provides better cooling.

- It also made room to add a 6-pin power/serial header (same as on the Front Panel card). Use this header with a USB-serial cable run the CPU board "barefoot" (without any other cards). The plan is to sell the CPU board by itself for half the price, for any little Z-duino projects you may have.

- I added jumper options to put BUSAK and BUSRQ on the bus in case they're needed. but there's an error in the silkscreen; the HALT and BUSAK are swapped. I'll fit it in the next batch of PCBs.

4. I've been "scheming" for a way to add a video/keyboard "terminal" card. I have several designs, none of which I'm entirely happy with. We can discuss them if anyone's interested.

5. A customer found a bug in the Dunfield BASIC; it can crash when handling strings. I haven't had time to track this one down yet. Anybody?

What have YOU been doing with the Z80MC?

Lee Hart

--
If happiness is on your mind, here's a daily list to find:
- something to do
- something to look forward to
- someone to love
- someone to take good care of
- and misbehave, just a little
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

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Thump thump.. testing 123 test test...

IS there any life or is it dead?

Allison

Scott,

must ahve better google foo....??

That is only a sample.? The trick is the 8073 was also called SC/MP-II.? Also helps
to try all three designations as National changed that over the years.

I have the 8a600 (the pmos first version), the sc/mp-II and the ins8073.
Interesting chip but slow.

Allison

Bill:
Happy to share and happy to bring back some fond memories for you.

The wire wrapping was very tedious and it wasn't just the one INS8073 board. There were three others that were wire-wrapped as well. I did't realize that RS had charged US$25 for a spool of #30 AWG Kynar wire. Yikes! Before they closed stores a few years ago, I grabbed about 4 spools for about US$3 each. I don't do much wire-wrapping these days but I do use the #30 AWG Kynar wire for rework and repairs. :)

I have an 1802 in my parts bins but never put one together nor have I done any programming on one. I've thought about it on and off over the past year, so I may at some time do so. :)

I have Lee's Z80 + SIO card set. No front panel. It seems to work well with CP/M. Josh did a phenomenal job on the firmware and software.

Peace and blessings

Paul:
You mentioned SC/MP; I used to have an SC/MP (INS8060) development board. I'm not sure where it ever went to. In my late teen years, I was given an INS8073 sample, which was the successor to the SC/MP (INS8060). The INS8073 had 2.5K of mask ROM with NIBL (NATIONAL Industrial BASIC Language) built in. I designed a whole computer around it, software and all. It was housed in a COMPUTER PRODUCTS I/O chassis and used multiple add-in boards that plugged into the back-plane. I acquired a dot-matrix printer that Larry from THE LITTLE COMPUTER STORE (S. Florida) retired and let me have for $100. I took it to college with me and wrote a word processor using the tiny BASIC. I recently pulled the main board out of storage, which is all I kept from the whole computer. Since there is little to no information on "the net" for the INS8073, I decided to document the project and posted a blog on it. You may be interested.?

Peace and blessings.

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ajparent1/kb1gmx wrote:

Of the possible member cards the one that sorta needs to be explored is
the 6502 and maybe 6800 or 6809.

When you look back the 1802, 8080/Z80 and 6502 reflect a significant number
and variations of machines. The three also reflect very different
programming mindsets.

Indeed, I'm working with someone on just such a thing. It's a Membership Card for the 6502, 6800, and 6809. The Front Panel cards are all the same; the CPU boards are necessarily different. The challenge so far is writing the software for each.

Lee Hart

--
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, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

Of the possible member cards the one that sorta needs to be explored is the 6502
and maybe 6800 or 6809.??

When you look back the 1802, 8080/z80 and 6502 reflect a significant number
and variations of machines.? Also the three also reflect very different programming
mindsets.

Allison

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