View Full Version : Amstrad PPC640's expansion box.

April 27th, 2006, 03:04 AM
Hello, I'am thinking about making an expansion box for my PPC640 to connect HDD to it. I have running 20 MB MFM drive with controller, but the main problem is that signals from expansion ports are unbuffered and unlathed so it will be nessesary to use eletronic.

Here is link to article how to make box with 3 exp. slots.

And here at the end of page are signals from expansion connectors:

I want to make it as simple as it can be, with one expansion slot. Has anybody ever made something like this and could help me a bit?

April 27th, 2006, 06:09 AM
I've done some work like this on a PCjr. We've gotten 8 bit ISA hard disk adapters and network adapters to hang off of a PCjr, which is no small feat.

For short distances, unlatched and unbuffered is not a big deal, especially on slower speed buses. Proper grounding and shielding is a much bigger deal.

There is an excellent book called "Interfacing to the IBM PC" by Lewis C. Eggebrecht. While not specific to the Amstrad, the concepts are the same. There are other books as well.

I am not an electrical engineer, but I sure wish I was ... (In addition to being a software engineer, of course.)

April 27th, 2006, 06:25 AM
Proper grounding and shielding is a much bigger deal.

Can you explain? I don't know electric terms in english...

I've heard about this book, but finding it in my country would be very hard.
It's really so simple? Just connect unbuffered signals to 74HC244, unlathed to 10k resistors and build little case?

April 29th, 2006, 05:54 AM
The key to any good design on any project is to protect the circuits from stray signals. On longs lengths of wire that run parallel to each other, it is possible to 'induce' (cause) a signal between two different wires, which is usually a bad thing.

MattCarp is a member here, and di the hard work on the PCjr to ISA bus adapter .. if he sees this maybe he'll throw in a few words.

May 25th, 2006, 06:46 PM
I also would like to build a PPC640 expansion boxs for me two PPC640's.
I have found some usefull information.

The Amstrad PPC Technical Reference Manual is available online at:


It looks like you could upgrade the com ports from 8250 uart (max 9600 baud) with 16550 UART thear could be problems with the BIOS but a IC socket could be used so the old 8250 UART coude be replased.

Also the inbuild CGA graphics adaptor can be disabled and a standerd VGA 16 bit ISA graphics adaptor could be used I have used 16 bit graphics adaptors in IBM XT's with no problems, also other 16 bit ISA cards may also be used.

I have two PPC640 one of them has an internal 40MB hard drive I would also like to clone

Dous anyone wont the work on it with me???


May 25th, 2006, 07:17 PM
Try to get a copy of the book that I referenced above - it is a real gem for this kind of a project.

I don't have enough of a EE background to make it work .. I need some basic education on how to use caps and resistors. (I understand their function, but not how to apply them to a circuit.) Some day ...

May 25th, 2006, 07:51 PM
I found some more info

May 25th, 2006, 07:58 PM
I have a copy of "Interfacing to the IBM PC" someware I will look for it.

May 25th, 2006, 10:08 PM
Where is hard disk card and HDD in your PPC? I'am interesting in doing that but I have no enough knowledge in electronic. I want to make only one expansion slot for HD controller. PPC have also EGA mode that's similar to VGA, but if you want VGA... you should make expansion box...

May 26th, 2006, 09:06 AM
one of my links is to a online copy of the ppc640 hardware manul and I think that the EGA option is for a EGA or VGA ISA card in a expansion box, it just disables the onboard CGA.

The PPC640 with the hard drive has a controler board added that conects the IDE hard drive to the main board.
It may be possable to copy it, the ROM on the controler would also need coping.

I have found someone that desigend and built a expansion box for his PPC640 in 1991 his name is called Steve Asher and I contacted him through his BBS.
he has emailed me all the documents about it and I am going over them.

I would like to put them here so you all can have a look

May 26th, 2006, 09:27 AM
Yes, true it's for external EGA. PC1640 had internal EGA, so i thought that PPC 'd have too. I'am interesting with the documentation.

May 27th, 2006, 02:08 PM
The book I have is "how to interface PCs by R.A. Penfold" not "Interfacing to the IBM PC" by Lewis C. Eggebrecht

May 27th, 2006, 02:36 PM
Here are the notes and drawings for building an expansion box for the Amstrad PPC512 / 640 portable computer from Steve A

74hc244.jpg Amstrad PPC Expansion Box - Rough drawing of 74HC244 IC pin layout

Here is a list of the files.

bottom.jpg Amstrad PPC Expansion Box - Drawing of underside of printed board layout

cardslot.jpg Amstrad PPC Expansion Box - Drawing of IBM card slot pin & signal layout, with notes

ppc-trm1.jpg Amstrad PPC Expansion Box - Cover pic of PPC Technical Reference Manual

ppc-trm2.jpg Amstrad PPC Expansion Box - Pic of Expansion Connector A in PPC Technical Reference Manual

ppc-trm3.jpg Amstrad PPC Expansion Box - Pic of Expansion Connector B in PPC Technical Reference Manual

ppc-trm4.jpg Amstrad PPC Expansion Box - Pic of Expansion Connector A, with my notes, in PPC Technical Reference Manual

ppc-trm5.jpg Amstrad PPC Expansion Box - Pic of Expansion Connector B, with my notes, in PPC Technical Reference Manual

ppc.txt Amstrad PPC Expansion Box - Overview and parts list

ppcwire1.txt Amstrad PPC Expansion Box - First description of wiring run

ppcwire2.txt Amstrad PPC Expansion Box - Second description of wiring run

top.jpg Amstrad PPC Expansion Box - Drawing of top side of printed board layout

wiring1.jpg Amstrad PPC Expansion Box - Pic 1 of my rough wiring notes

wiring2.jpg Amstrad PPC Expansion Box - Pic 2 of my rough wiring notes

wiring3.jpg Amstrad PPC Expansion Box - Pic 3 of my rough wiring notes

The Amstrad PPC Technical Reference Manual is available online at

May 27th, 2006, 06:53 PM
I have looked up the HC series and found out that thay have a small fan-out of 2.5, that means that a HC series IC can only run 2.5 orignal 74 series ic's or 10 LS series ic's.
I have found a TTL series that has about the same fan-in as the HC but a lower propagation delay and a fan-out of 5, its the 74ALS series.

Why I think it should be used is becos I think that the ISA card's may use orignal 74 series ic's or lots of LS series ic's and exceed the current rating of the output of the 74HC244.

The 74HC244 and 74ALS244 should be pin compatible.

I found a web page that showes the product life cycle of TTL and CMOS Families and 74ALS244 is not obsolete.

I have looked at the cost of the ic's
74HC244 0.32 UK 2.22 in zloty
74ALS244 0.51 UK 3.52 in zloty
I got the price from RS Components UK www.rswww.com there is a
RS Components International www.rs-components.com there is a RS in Poland

May 27th, 2006, 10:12 PM
I found a data sheet for the 74ALS244 www.ortodoxism.ro/datasheets/philips/74ALS244A-1.pdf

and 74HC244 www.standardics.philips.com/products/hc/pdf/74hc244.74hct244.pdf

May 27th, 2006, 11:22 PM
thare are controlers that were made to work in the IBM XT that would work in the PPC640 expansion box I am using a SCSI one in my XT and ABC Computers in the USA sells a 8 bit ISA hard drive controler for $48 us dollers you could probley use a 500MB hard drive on it or with some clever software upto about 8GB I think.

under coltrolers, PC-XT IDE controler

Also a 2.5 inch IDE laptop hard drive could be used to keep things small and power requirments down.

I am also looking in to how to upgrade the com ports from a maxamun speed of 9k to 115k.

May 27th, 2006, 11:40 PM
I found a 8 Bit IDE Hard Disk Adapter for $10 us dollers at

Western Digital 8 bit ISA hard drive controler for $10

CD-ROM Controller for Pan,Sony,Mitsumi by SunMoonStar not IDE for $10

a big list of 8bit cards

8 Bit Floppy Drive Interface Card for 1.44mb disk drives $5

8 Bit EGA/LPT/Extended Memory Card $10http://computerjunk.com/catalog/items/item164.htm

Everex Micro Enhancer Deluxe EGA/VGA VCard $10

SIIG E-Lan 100 8-Bit Ethernet Card (Coax or AUI) $10

XT Style 150 Watt Power Supply $5

May 27th, 2006, 11:44 PM
I found a data steet for the 8 bit ADP50 IDE comtroler.

Full setup information

May 28th, 2006, 12:27 AM
Mh. Wired... ;)

May 28th, 2006, 06:24 AM
That's a lot to digest .. I'm going to come back to your posts later tonight and try to digest them.

Is the Penfold book good? Extra reference material never hurts.

8 bit IDE might be a trap .. You need to find a drive that has an 8 bit transfer mode. Only the very oldest IDE drives do that ... newer drives expect 16 bit transfers, and don't implement the 8 bit transfer part of the specification because it is optional.

I've had 8 bit SCSI cards running on my expansion adapter with brand new drives. They are a better bet.

May 28th, 2006, 04:36 PM
I did not know that there was a difference between XT and AT IDE.
Using an 8 bit SCSI card would be easyer but I have not found any more.

I found a page "How to connect an IDE disk to a microcontroller using an 8255"
it sed that "You COULD even implement an IDE interface with an 8-bits only data bus. That would mean that you use only half the disk capacity (the lower bytes of the 16-bits-wide bus) but that should work."

so you mite just lose 50% of the hard drive space

And http://www.gaby.de/gide/IDE-TCJ.txt sed
"In a PC the drive is accessed directly
by the CPU via I/O accesses to registers internal to the
drive. The disk data is transferred via the 16-bit data
bus, but for compatibility to the older systems (again!)
only 8 bits are used for command and status information.
Besides the data bus, there are the standard Intel-type data
strobe signals (/IORD and /IOWR), a few address lines, and
some special signals. The connector is a 40-pin header, not
to be confused with the XT-type IDE interface connector,
which is also a 40-pin header but needs somewhat different
hardware and totally different software!"

So could an adapter be used to connect a AT type (16 bit) IDE hard drive to a XT type (8 bit) controler.

May 28th, 2006, 05:34 PM
I found this

The XT and ATA versions have standardized on 40-pin connectors and cables, but the connectors have slightly different pinouts, rendering them incompatible with one another.

In most cases, you must use the type of IDE drive that matches your system bus. This situation means that XT IDE drives work only in XT-class 8-bit ISA slot systems, AT IDE drives work only in AT-class 16-bit ISA or EISA slot systems.
A company called Silicon Valley offers adapter cards for XT systems that will run ATA IDE drives. Other companies, such as Arco Electronics and Sigma Data, have IDE adapters for Micro-Channel systems that allow ATA IDE drives to be used on these systems. (You can find these vendors in Appendix A.) These adapters are very useful for XT or PS/2 systems, because there is a very limited selection of XT or MCA IDE drives, whereas the selection of ATA drives is virtually unlimited.

The ADP50l 8 bit ISA IDE controler is made by SILICON VALLEY COMPUTER, INC. and only works with AT IDE hard drives and costs $10 US dollers.
so you should be able to use 2 standerd IDE hard drive upto 504MB with a transfer rate of 3.3m/sec.

A larger hard drive could be used but you could onley use 500MB of it without some clever software.

An IDE CD ROM could be used.

May 28th, 2006, 05:54 PM
I read up on SCSI standards and using a moden SCSI device in a SCSI 1 card will work very well but 8 bit SCSI cards and SCSI hard drives cost more.

I found "8 Bit ISA SCSI ADAPTER" Made by Emerald for $35 US dollers

And "SCSI long card 8 pin ISA" $45 US dollers

And "Future Domain TMC-840 SCSI 8 bit ISA CARD" $40 us dollers

BIOS update for Future Domain TMC-840

Future Domain TMC-840 $40 US dollers

Future Domain TMC-840 setup info
"The TMC-840 require software for Low Level Formatting. Future Domain shipped it's "Disk Maestro" software utility with these Host Adapters."

May 28th, 2006, 06:07 PM
I think you can do better looking on eBay .. I don't think I've ever paid more than $10 for an older, 8 bit SCSI card. You definitely want one with a boot EPROM though. A lot of 8 bit SCSI cards were used for CD-ROMs and as such, they might not have a boot EPROM.

As for the drives, I'm not suggesting that anybody go out and spend $1000 on an enterprise class 10000 RPM Ultra SCSI 320 drive to connect to an 8088 class machine. There are plenty of smaller, more appropriate drives floating around.

The nice thing about the SCSI interface and drives is that you can find newer drives than the machine you are connecting them too .. Look at any machine using an MFM style interface with a corresponding drive. If the drive craps, you are looking for another 15 to 20 year old drive to replace it. If that had been a SCSI interface you could be looking for a 5 to 20 year old drive, which gives you many more choices. And your replacement won't be on it's last bits either.

Terry Yager
May 28th, 2006, 06:09 PM
IIRC, some of the earlier IDE drives were selectable between 8- & 16-bit modes. (I can't recall any of the model numbers right now).


May 28th, 2006, 06:39 PM
Thare are cable adapters that let you use a 2.5inch SCSI or IDE hard drive.
This would let Luke be able to make a small expansion box with the hard drive in it.

I found one 8 bit ISA SCSI controler at ebay.com USA stating bid $19.99 with $22.00 shiping to the UK.

June 4th, 2006, 12:02 AM
I don't know if I could really make exp. box, I know only basic things about electric... My idea is just to make it as simple as it can be - with one slot.

June 4th, 2006, 04:24 PM
I am still working on the design of the interface but it would be the same if you wanted 1 or more ISA slots.
The only difference would be needing a bigger power supply for the extra cards.
I am planning on using an old "riser card" it has 3 ISA sockets and the edge connector that I can solder wires to.

By the way what ISA card did you want to put in your amstrad PPC640.

June 10th, 2006, 05:39 AM
I have worked out the interface circuits and I will put it online when I have cleaned up my notes.

June 12th, 2006, 06:27 AM
I was wrong a 74ALS244 can not replace a 74hc244.

January 12th, 2018, 01:25 PM
Hi I just got myself a nice PPC 640 and wondered if the expansion ever got made or if anyone still supplies them or can advise how to make one? I'd really like to add a hard drive somehow. Also is there anyway to upgrade to a better LCD screen?

Thanks for any help at all. :)