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On 2023-09-07, dxforth <
dxforth@gmail.com> wrote:
> On 7/09/2023 1:50 pm, Jeff Jonas wrote:
>>> Let`s not forget the Z80 itself was a new processor
>>> built upon an old design and became popular for that reason.
>>
>> Yes, no, kinda, maybe?
>> 8080 compatibility definitely helped on the software side,
>> running CP/M and such.
>>
>> But the Z80`s hardware was tremendously easier to use,
>> almost like silicon-chip Lego, thus becoming the favorite for
embedded systems
>> such as "smart modems", SCSI controllers, terminal servers.
>> In a way, the Z80 peripherals were "the tail wagging the dog"
>> because they were so popular, particularly the SIO dual-channel
serial I/O chips.
>>
>> Z80 hardware features:
>>
>> +5 volts only, no +/- 12v
>>
>> single phase clock: no special clock generator required
>>
>> Z80 native peripheral chips self-arbitrated DMA and vectored
interrupts via daisy-chain.
>> No interrupt controller required.
>>
>> built in dram refresh cycle, making RAM interfacing easier.
>>
>> The Z80 signals were so direct and easy to use
>> that they formed the basis of the STD bus (which was later extended).
>>
>> I/O address space was separate from the 64k memory address space
>> due to IN, OUT instructions asserting the /IORQ signal instead of /MREQ
>>
>> and other things :-)
>
> I worked in telecom. Equipment originating from Europe (Siemens) tended to
> use the 8085 while the Japanese (Ando) used the Z80. So not a great deal
> of difference between them in that market. Unlike Zilog, Intel appears
> to have lost interest in the 8080 line. I wasn`t aware the 8085`s `undoc`
> instructions were actually new instructions which Intel, in their wisdom,
> chose to disown.
What about Steve Ciarcia`s (sp?) SB180 single board computer as featured in
Byte Magazine (before it`s demise). He had a column called "Circuit
Cellar", I think.
As I recall, though, it used a Hitachi chip of some sort rather than a Z80.
Well, CP/M faded from the scene far too early in my opinion, but I still use
jstar to satisfy my WordStar finger memory from thsoe days.
pH in Aptos
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