Re: [EE] New retro-computing project

Thanks! I wire wrapped something like that using the MC6802 in the late
1970s. I remember how clever byte wide RAM and EPROM were. The pin outs of
EPROM and RAM were the same except for a few pins. Various sizes of RAM
and EPROM  also had the same pinout except for a few pins. Jumpers
selected the type and size of memory. There was also byte wide EEPROM in
the 28 series (as opposed to 27 for EPROM). In my wire wrapped board, I
used a separate UART, a 65 something or another. Your board has the UART
in the CPU. The MC6802 has the full 16 bit address on the pins, while this
chip uses Address Latch Enable to multiplex the address onto the 8 bit
data bus. As I recall, that's also what the 8088 did, as opposed to the
8086. But, it's been a while. I did have to deal with ALE on a Z80
project.

One thing I really like about microcontrollers is that the address and
data buses stay inside the chip. With systems with external memory and
I/O, it is a real pain to find a problem when it affects one of the buses
since NOTHING works. With microcontrollers, I can put in a power on self
test that tests all the external devices and lets me know they are
working.

The MC6802 wire wrapped board turned into a couple products. The schematic
of one is at
https://bh.hallikainen.org/uploads/HaroldHallikainen/20130416125553.pdf .
This was designed with Dasoft schematic capture and PCB layout software
running on a Cromemco CP/M computer. Long time ago!



Harold
https://w6iwi.org


On Tue, March 10, 2026 2:49 pm, Isaac Marino Bavaresco wrote:
> PDF schematics available.
>
>
> A textual description will take some time.
>
>
>
> Cheers,
>
>
> Isaac
>
>
>
> Em 10/03/2026 17:48, Harold Hallikainen escreveu:
>
>> Interesting! Do you have more of a description and a pdf schematic?
>> Grabcad is pretty nice! I have done schematic and PCB layout with KiCAD
>> but have not tried the 3D modeling.
>>
>> Harold
>>
>>
>>
>> On Tue, March 10, 2026 12:29 pm, Isaac Marino Bavaresco wrote:
>>
>>> Hi All,
>>>
>>>
>>>
>>>
>>> I just published on GitHub the design of an 80C32 board that I
>>> designed last year.
>>>
>>> It's a project just for fun and to remember the old times, but it
>>> might interest someone.
>>>
>>> <https://github.com/Ibavaresco/80C32>
>>>
>>>
>>>
>>>
>>> Cheers,
>>>
>>>
>>>
>>> Isaac
>>>
>>>
>>>
>>>
>>> --
>>> O software antivírus Avast realizou uma checagem de vírus neste
>>> e-mail. www.avast.com -- http://www.piclist.com/techref/piclist PIC/SX
>>> FAQ & list archive
>>> View/change your membership options at
>>> https://mailman.mit.edu/mailman/listinfo/piclist
>>>
>>>
>>>
>>
>
> --
> O software antivírus Avast realizou uma checagem de vírus neste e-mail.
> www.avast.com --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> https://mailman.mit.edu/mailman/listinfo/piclist
>
>


-- 
Not sent from an iPhone.
-- 
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
https://mailman.mit.edu/mailman/listinfo/piclist