RIZ180, a simple Z80180 SBC for RC2014

[Bill Shen]

Someone gave me six Z8018008PSC and a request to build a cheap RC2014-compatible SBC with through-hole components and no CPLD.   Z180 is so well integrated that seems to be a reasonable request, but I encountered two challenges as I went down the design path:
1.  DIP64 is 70mil lead pitch rather than the standard 100mil pitch.  I didn't want to solder it directly on newly developed pc board, but fortunately DIP64 socket with 70mil pitch is readily available on eBay and cheaply, except the order takes long time to arrive.
2.  Address 19 is not bonded out on DIP64.  This makes it difficult to run ROMWBW with direct memory mapping.  I made a design decision to not run ROMWBW, but port CP/M2.2 and CP/M3 by rework existing Z80 software

I name the board RIZ180, after the person who gave me the parts.  Here are the features of RIZ180:
* Z80180 at 7.37MHz
* 128K RAM
* 128K EPROM
* IDE44 for compact flash drive or DOM
* 2 serial ports, 1 SPI port
* 3 RC2014 expansion slots plus a RC2014 backplane extender
* All through-hole components, no CPLD
* 4"x4" 2-layer PC board
* CP/M2.2 and CP/M 3 ready

Z180 is so well integrated, it almost needs no glue logic, almost.  Can't get around needing a 2-input OR gate for RAM/EPROM decoding, so I might as well added a 74138 to have a CF interface.  Disk-on-module (DOM) interface is mirror image of CF interface, so with 1/2" standoffs and 90 degree connector, a DOM disk can be mounted on the bottom of the board.

Z180 has 2 serial ports and a SPI port.  Channel A of the serial port has handshake signals.  The handshakes have caused so many problems that I designed channel A specifically for CP2102 USB adapter which is inexpensive and have a proven handshake function.

Here is schematic and board design.  Rev0 engineering prototype is out to JLCPCB.

[Mark T]

I find the single in line turned pin sockets useful for odd size or out of stock dual in line sockets. Takes a little extra care to make sure they are mounted vertical and correctly aligned between a pair of socket strips but quite good for development work.

Mark

[Bill Shen]

I have turned pin sockets except their diameter is 70mil.  Probably can squeeze them a bit to fit or make slightly staggered row, but getting the socket from China is easier, if not a tad slow.
  Bill

[Mark T]

Sorry yes, I didn’t realise this was 70 mil pin pitch and thought you meant 700 mil between the two rows.

[Bill Shen]

It is the "shrink DIP" package, apparently quite popular although only examples I can think of are V9958 and Z80180.
  Bill

[David Richards]

I have a Hitachi 6303 in a 64 pin shrink dip package, its all I have left from a project back in 1990 or there about, may have the iar source on a floppy maybe. The project listened for dialled numbers and calculated call costs using an area code database and timer. D

[Sergey Kiselev]

Toshiba offered Motorola M68000 compatible CPUs in both Shrink DIP-64 package and 100 mil lead pitch DIP-64 package (aka "Texas Cockroach", see page 9 here: https://archive.computerhistory.org/resources/text/Oral_History/Motorola_68000/102658164.05.01.acc.pdf)

The Z180 predecessor - Hitachi HD64180 also had a Shrink DIP-64 package

[Bill Shen]

Received RIZ180 pc boards and built one up.  It is communicating to TeraTerm terminal.  I'm working on porting a simple monitor to it.  However, there is a problem.  Take a look at the picture, can you spot the problem? 
  Bill

[Eric Dittman]

You still got it soldered in! :-)

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[Wayne Hortensius]

My first thought was "is that distortion from a closeup lens"?

My second thought was "how on EARTH did you manage to solder that in"?
(Well done, by the way -- and shudder!)

Are those pads on 75mil spacing rather than 70?

Wayne

[Bill Shen]

I created the footprint with 75 mil center instead of 70mil, and I knew perfectly well it should be 70mil center.  Must be having a "senior moment".

Fan out the pins, apply pressure to the DIP and adjust leads until they fall in; solder a few pins to hold them; then work on the other row.  It is like picking lock--one tumbler at a time.
  Bill

[Richard Deane]

Alos not all chips are aligned the same way . RAM and ROM are left poInting, others are right pointing. It is good practice to keep to one direction/

[Greg Holdren]

Actually it is more important to place the ICs to aid in signal lay out and flow.

Greg

[Bill Shen]

Built up 2nd RIZ180 to check out the DOM interface.  Since DOM connector is mirrored of CF connector, it needs to be mounted at the bottom of the board.  It also needs standoff to keep the DOM off the bottom.  The pictures below show the two configurations.  The DOM in this case is an Apacer 1G with 90 degree mount.

I have ported CP/M2.2 to both boards; both DOM and CF are working properly.
  Bill

[Bill Shen]

Rev1 of RIZ180 fixed the embarrassing 64-pin shrink DIP footprint mistake.
  Bill