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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 22nd Jan 2013, 12:04 am   #21
malvision
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Default Re: Maplin Z80 SBC

I have the 1987 Maplin catalouge and the board is pictured in this with a description.

The Maplin CPU Module can accept up to 8k of memory which is decoded in 2k(2048 bytes)blocks.The first block contains the operating system in ROM or EPROM and the second,third,fourth blocks can either RAM or ROM.Static or CMOS 2K RAMS may be fitted(totalling 6k) and battery backup is availble,via switches,for CMOS data retention,if required.Both Z80 or Z80A processors can be fitted,and the system clock has facillities for different size crystals to suit,eg 1MHz crystal for Z80 or 2.4576MHz crystal for Z80A
A keyboard/display decoding IC can be fitted allowing for small key or large (64-key)type keyboards(or sensors)for data input.This ic can also drive seven segment LED displays.This interface can scan up to 64 keys-expandable to 128 with suitable decoding-and sensors or strobed keys may be used.Two key lockout and N key rollover can be programmed,and keyboard entries generate an interrupt(NMI) to the Z80.Either four or eight(programmable)7 segment displays can be added with blanking facilities,and all connections are made via a 26-pin IDC socket.
Four decoded I/O select lines are available and all data and address lines are buffered before being brought out to an expansion edge connector.All of the Z80 control lines are available ,most of which are buffered,including a system CLOCK output,RESET output,SYSTEM RESET input and a switched NMI input.The NMI can be taken from iether the KBd/display interface or directly from the expansion connector

Z80 CPU module PCB 13.00
Z80 CPU MODULE kIT 30.95 1987 price
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Old 7th Jun 2013, 4:59 pm   #22
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Default Re: Maplin Z80 SBC

I still have a working Maplin SBC I have recently gone through the EPROM and entered all the data into a spread sheet, let me know if anyone wants it. Also have the GJ25C serial interface board but have lost the EPROM that it uses would love to get this working if anyone has the firmware.
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Old 9th Jun 2013, 9:05 pm   #23
Alf Fisher
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Default Re: Maplin Z80 SBC

Hi Bazil2112,
I would be interested to have a copy of your spreadsheet of the Maplin code.

Alf
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Old 11th Jun 2013, 6:38 pm   #24
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Default Re: Maplin Z80 SBC

Is it possible to directly upload images onto this site or do they have to be links to offsite image hosting sites? I'd be happy to post a picture of my Maplin Z80-SBC here. If we can keep this thread ticking over maybe someone who has the MS12 eprom will eventually turn up.

I believe I reconstructed the source of the M12 (not MS12) code not long after Alf originally expressed an interest in the system, but I have since changed computers and it isn't on the one I presently use - in any case it's the MS12 eprom - the version which supports the add-on serial board kit - which is the one that I don't have, and several people seem to need.

Those of you looking for the MS12 eprom, bear in mind that it was meant to work with the companion PC IDE software which would also have to be found or re-engineered.
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Old 19th Jun 2013, 10:59 pm   #25
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Default Re: Maplin Z80 SBC

Hi Alf,

new to these forum things, how can i get the spreadsheet to you?
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Old 19th Jun 2013, 11:04 pm   #26
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Default Re: Maplin Z80 SBC

I used to have the MS12 eprom but stupidly put it in a box of other eproms and the label fell off so it's there somewhere but we are talking dozens of eproms, there was also a floppy disk with it that I would dearly like to have as well.
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Old 21st Jun 2013, 7:50 am   #27
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Default Re: Maplin Z80 SBC

If I tell you that the eprom would be a 24-pin 2716 or 2732, would that narrow it down for you? And then, if you have an eprom reader, try searching through the eprom code for the string 'MS12'. I have a vague memory that the M12 eprom contained the string 'M12'.
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Old 21st Jun 2013, 2:56 pm   #28
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Default Re: Maplin Z80 SBC

Hi Bazil,

You can attach files to posts here if you click Go Advanced rather than just using the Quick Reply. You'll need to put it in a zip file as spreadsheet files are not one of the accepted file types.
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Old 21st Jun 2013, 9:27 pm   #29
Alf Fisher
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Default Re: Maplin Z80 SBC

Hi Siriushardware,

That is assuming that Bazil has a means of reading EPROMS.
I have a programmer so maybe Bazil would agree to lending me the EPROMS to find one that is it. I can also read 3.5in and 5.25in floppy disks on my old 486 PC.

Bazil,

I will send you an email so you can reply.

Regards,
Alf
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Old 21st Jun 2013, 11:03 pm   #30
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Default Re: Maplin Z80 SBC

Hi Alf/Siriushardware

i have sent you the excel spreadsheet, I don't have an eprom reader sadly so i had to sit down one night and go through all memory locations and put them into the spreadsheet, it was a bit of a labour of love but it was something i have been meaning to do for a long tome as i was worried that the eprom might fail. I will try to dig out the MS12 eprom but i used to repair printers and fax machines and any that i scrapped i used to dismantle and keep all the useful parts (yes I'm a bit of a hoarder) so there are dozens of eproms to go through.
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Old 22nd Jun 2013, 9:23 am   #31
Alf Fisher
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Default Re: Maplin Z80 SBC

Hi Bazil,

Received the Excel file ok. Many thanks.
It certainly was a labour of love to painstakingly enter all that data by hand. It must have taken hours!
I assume column D is decimal address and column F is Hex address and column G is the data.

I am curious to know the significance of the green markers in some of the data cells.

Is it all blank (FF) after 0523H

Was it a 2K EPROM? The reason I ask is that your addressing goes beyond 07FFH but not as far as 0FFFH. I see that you used the calculation facility in Excel to generate the hex addresses. Good idea!

Best wishes,
Alf
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Old 22nd Jun 2013, 11:34 am   #32
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Default Re: Maplin Z80 SBC

Hi Alf,

It didn't take as long as i thought thanks to excel doing the hex column for me, must admit i had been putting it off for a while, reading your post spurred me on to get it done.

you assumed correctly about the columns i should have put headings on them.

i can't remember why the green markers are there sorry.

yeah all blank after 0523H and it is a 2k rom.

MS12 next, though i never got the GJ25C serial interface to work, all it ever did was overheat, though saying that it did actually connect to a pc once for a few seconds then failed, I checked the circuit over and over and even replaced all of the components but it never worked again, problem is i have so many unfinished projects going on.
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Old 22nd Jun 2013, 8:22 pm   #33
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Default Re: Maplin Z80 SBC

Quote:
Originally Posted by Alf Fisher View Post
Hi Siriushardware,

That is assuming that Bazil has a means of reading EPROMS.
I have a programmer so maybe Bazil would agree to lending me the EPROMS to find one that is it. I can also read 3.5in and 5.25in floppy disks on my old 486 PC.

Bazil,

I will send you an email so you can reply.

Regards,
Alf
Reading Baz's previous post, it appears that he has unfortunately LOST the companion PC IDE disc which is needed to work with the MS12 eprom: But identification / recovery of the MS12 eprom code would be a further step in the right direction, and one less thing to have to find.

Baz, can you remember:

Was the MS12 eprom for the CPU board, plus serial 8251 board, PLUS the keypad/display PCB, or was the PC software and serial board used as an exclusive, alternative way of getting code into the CPU board?

The original CPU card + keypad / 7 segment display card system was the original means of getting code into the system - you typed it in in hex. But obviously, your own programs could also use the keypad and 7-segment display as well.

I'm wondering if the MS12 eprom:

1) Still supported the keypad and display, but added support for the serial board,

or

2) Abandoned support for the keyboard and display, concentrating instead on communicating with / via the PC IDE software. I/O would then be solely by means of whatever hardware you connected to the edge connector.
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Old 22nd Jun 2013, 8:26 pm   #34
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Default Re: Maplin Z80 SBC

Quote:
Originally Posted by Paul Stenning View Post
Hi Bazil,

You can attach files to posts here if you click Go Advanced rather than just using the Quick Reply. You'll need to put it in a zip file as spreadsheet files are not one of the accepted file types.
Are image files acceptable as direct attachments, and if so,

Which file types are accepted, and-

what is the site's maximum preferred pixel resolution for such images?
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Old 22nd Jun 2013, 9:30 pm   #35
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Default Re: Maplin Z80 SBC

Image files will be resized to 800x600 by the forum software so you can upload any reasonable size. If you need to upload a higher resolution than this and don't want it resized, put the images in a zip archive or PDF document.

A list of file types and limits is displayed on the attachment upload screen.
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Old 24th Jun 2013, 8:21 pm   #36
Bazil2112
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Default Re: Maplin Z80 SBC

Think i had a moment of clearing out and threw a load of floppy disks out and now regret it!

The MS 12 did not support the keyboard as well as the interface as i remember so just abandoned the use of the keyboard/display. Managed to borrow a eprom programmer off a friend he's bringing it into work tomorrow his memory is none to good though but hopefully i will be able to start sorting through the eproms soon.
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Old 24th Jun 2013, 9:46 pm   #37
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Default Re: Maplin Z80 SBC

Quote:
Originally Posted by Bazil2112 View Post
Think i had a moment of clearing out and threw a load of floppy disks out and now regret it!

The MS 12 did not support the keyboard as well as the interface as i remember so just abandoned the use of the keyboard/display. Managed to borrow a eprom programmer off a friend he's bringing it into work tomorrow his memory is none to good though but hopefully i will be able to start sorting through the eproms soon.
You don't by any chance still have the PC (or the hard drive from it) that you had it installed on? At that time I suppose it would have been either DOS or Windows 3.1 software, so not too difficult to move from one machine or disc to another.

My Maplin SBC is married to a 'Microprofessor' I/O board that I picked up when Greenweld were selling them off years ago. The board has a Z80-PIO, Z80-CTC, and an 8251 UART on it, and amazingly none of the I/O addresses clash with any of the hardware on the Z80-CPU card so it just works.

I wrote a bit of code for it to load Intel Hex format code in from the 8251 on the Microprofessor I/O board and I put that code into the empty space in the original M12 eprom. To make that code work on Maplin's own serial board would probably just involve changing the I/O address used to access the 8251 - snag is, I wrote that code using the Z80 cross assembler I had for the Atari ST and that machine is itself mothballed most of the time now.

Good luck with identifying the eprom.

Last edited by SiriusHardware; 24th Jun 2013 at 9:59 pm.
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Old 24th Jun 2013, 10:18 pm   #38
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Default Re: Maplin Z80 SBC

Alf, Baz, may I suggest you follow the link in post #20 in this thread? I had not noticed that post until now.
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Old 25th Jun 2013, 9:25 pm   #39
Bazil2112
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Default Re: Maplin Z80 SBC

Thanks Sirius, seems there is a monitor prog on there which i have installed on my pc and after a bit of scrouting around i have found an assembly file on the site which looks pretty much like the original MS12 firmware here, had a sort through all the eproms last night narrowed it down to about 20 but may not need to find it now anyway.
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Old 25th Jun 2013, 10:15 pm   #40
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Default Re: Maplin Z80 SBC

Quote:
Originally Posted by Bazil2112 View Post
Thanks Sirius, seems there is a monitor prog on there which i have installed on my pc and after a bit of scrouting around i have found an assembly file on the site which looks pretty much like the original MS12 firmware here, had a sort through all the eproms last night narrowed it down to about 20 but may not need to find it now anyway.
In the zip file originally linked to, there's also a 2048-byte file which I believe is in raw binary format. It's just the right size to fit into a 2716 eprom.

Looking at that source you referenced, it does seem to mention the keypad / display I/O addresses as well as the UART addresses, so maybe MS12 did support that hardware after all.

Thanks, incidentally, to jgharston, who posted the link and appears to have been the person who recreated the source.
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