non-CP/M Z80 board

[Allison]

>
>Subject: Re: non-CP/M Z80 board
>   From: ard at p850ug1.demon.co.uk (Tony Duell)
>   Date: Thu, 19 Jun 2008 04:42:01 +0100 (BST)
>     To: cctalk at classiccmp.org
>
>> > I think the chips under discussion were the 8085 specialty chips,
>> > 8155, 8355, 8755, etc.  Got tubes of those?
>> 
>>    I've got a dozen or so 8755s, two or three 8155s, and no 8355s.   
>> Not tube quantities, unfortunately.
>
>IIRC the 8355 was the mask-progeammed part, so it's not suprising you 
>don't have any of those, If you did, they proably wouldn't contain the 
>code you wanted :-). 

Yes, but it' still useful as an IO device with 16 IO port lines that could 
individually set for input or output.

>The 8755 was the EPROM part, and at least one 
>version had a quartz windo for erasure (I don't know if there was an OTP 
>type). The 8155 was RAM. All had I/O as well.

There was never an OTP, all were windowed Eprom devices.  

the 8155 and the '56 were the same device save for CS polarity.  they
are very useful with 256bytes ram, a programable timer/baud rate generator
and 22 IO pins that can be set as output, input or strobned outpus and inputs.

>There's also the 8156, which is the same as the 8155 (RAM + I/O) but with 
>an active-high chip select. Not as common as the 8155.

Not as widely used but I have a bunch.

>Of course you can use normal RAM and EPROM with the 8085 is you add and 
>address latch. An 74x373, or the 74x573 which as a saner pinout, is a 
>common choice.
>

There was also the 8185 wich was a 1Kx8 ram with muxed address/data.  
Those were uncommon as intel was the only supplier.

The 8085A (or A-5), 8755, 8155 in three chips gave 256bytes ram,
2Kbytes Eprom, 38 configurable port lines, A timer/baudrate generator,
4 interrupt lines and the handy SID and SOD IO pins.  Very handy 
for small applications.  The base part ran at 3mhz (3.072mhz) and 
the faster A-5 was a 5mhz (there were 6mhz HmosII and CMOS parts 
later).

Substitute a 8088 (or V20) and 8284A for the 8085 and you had a 16it 
cpu with all the Eprom, ram and IO listed.


Allison

>-tony