What kind of IC is this
mcguire at neurotica.com
Wed Dec 31 09:57:11 CST 2008
On Dec 31, 2008, at 9:27 AM, Jules Richardson wrote:
>> Ok, i don't know much CPUs with onboard ROMs, but I think it
>> should work
>> with Zilogs Z8 with on-chip ROM - or am I wrong at all?
> That reminds me - I keep meaning to look up details on the Z8. I
> was told once that it was just a Z80 with on-board ROM, but that
> never explained why I had one in the junk box marked "Z8 ROMless"...
"The Z8 is an embedded version of the Z80" is a very common
mistake, one I've even seen in print in magazines. Nothing could be
further from the truth...it is a completely different architecture
that doesn't even bear a passing resemblance to the Z80.
It's a pretty neat register-file-based architecture, kinda fun to
program. They've been around for a long while, and are still current
products. The current Z8 implementations are available in low-pin-
count packages and are pretty fast. What's lacking is free
development tool support, which is sad, and very unusual for today's
Zilog did a nice BASIC, which they shipped in a mask-ROM version
(Z8671) which Steve Ciarcia had a ball with in several of his BYTE
Magazine articles. There's also a Forth implementation which I've
messed with, after having typed in the entirety of a faded printout
of a hex dump in order to get into digital form...that was tedious.
Your "Z8 ROMLESS" chip is just that; a Z8 microcontroller that is
designed for use with an external ROM. Still others (Z8603, Z8613)
are available which have a 24-pin EPROM socket permanently mounted
atop the ceramic 40-pin DIP, with the die well pushed off to one side
to make room for it. It's neat. I've got quite a few of those;
they're what I use to mess about with the Z8671-shipped BASIC, and
the Forth system I mentioned above.
Here's a pic of a quickie board I threw together to exercise both
the BASIC and Forth implementations, using one of those "EPROM socket
on top" chips:
Port Charlotte, FL
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