MFX mass-storage add-on

Modern, Memotech inspired, hardware projects
Martin A
Posts: 594
Joined: 09 Nov 2013 21:03

Re: MFX mass-storage add-on

Post by Martin A »

stephen_usher wrote: 11 Jul 2022 21:22 With respect to the 512K memory. If the MTX only has 32K on-board how is the memory mapped?
The MTX memory map in "ROM mode" has room for 16 pages of 32k and then 16k fixed memory. The MTX memory test has a bug if all 16 pages are full, and reports no paged ram found ram as a result. So MFX maps in 15 full pages and one half page. Since there is already some memory in that area it actually means, either 32k or 64k of the expansion RAM is unused.

In "RAM mode" the pages are 48k in size, again with 16k fixed. the 480k of the 512k is used to create 10 full 48k pages in pages 1 to 10. In a MTX 500 the remaining 32k fills the gap in page 0 to give CPM it's full 64k compliment. On the MTX 512 that 32k is allocated to partially fill page 11 instead.

So either system has 512k in basic, in CPM the MTX 500 has 544k (64k base + 10 x 48k paged), the MTX 512 has 576k (64k base + 10 x 48k & 1x 32k paged). The CPM boot code inherited from ReMemotech/ReMemorizor allows for 256k or 320k Ram drive F: to be created in that paged memory in CPM.

The screen shot below is from the Excel spread sheet I was using to visualise the movement of RAM while working on the GAL code. The way the blocks move is to match the original Memotech scheme. That makes for some seriouly messy equations, that thankfully WinCUPL can optiminse, even then the chip select logic hits 16 terms.

16 is the maximum terms available on the largest cell in the 22V10. Which is why there's no jumper option for the MTX512S2 or RS128.
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stephen_usher
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Re: MFX mass-storage add-on

Post by stephen_usher »

Thanks!
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gunrock
Posts: 124
Joined: 28 Oct 2020 21:17

Re: MFX mass-storage add-on

Post by gunrock »

Please add me too, Dave.
Steve G
Danish-keyed Memotech MTX 512, CFX II and loving it
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Dave
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Re: MFX mass-storage add-on

Post by Dave »

To whet your appetites for MFX . . . .

I have done a first draft of an "Operator's Guide". It is modelled on the original FDX Operator's Guide and cribs most of its contents, including pretty comprehensive coverage of CP/M, starting from a pretty basic level, it is probably too simplistic for many - but just ignore the parts that you aren't interested in.

You probably do want to read the installation guide (Chapter 2), the SDX BASIC USER commands (Chapter 16) and the WIZnet network stuff (Chapter 17).

If you spot any glaring errors or think that anything's missing, please let me know

It is available at the top of this page http://primrosebank.net/computers/mtx/p ... _usage.htm

regards
Dave
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Dave
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Re: MFX mass-storage add-on

Post by Dave »

Time for another update . . . .

If you have read the MFX engineering page recently, you will see that there turned out to be a couple of minor issues with the first run of PCBs. The V1 PCB would have needed a couple of patch wires fitted, the patched board would have worked fine, but I didn't want to supply the PCB with ugly patch wires - even though they would have been on the bottom side and never seen once the board has been fitted.

An updated PCB has been manufactured, I have now received the revised boards and am starting to assemble them. I have also ordered up a number of 3D printed end plates in different materials so that I can pick the most suitable. They should be here in 7-10 days, at which point, I should (fingers crossed!), be ready to ship the first orders.

regards
Dave
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gunrock
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Re: MFX mass-storage add-on

Post by gunrock »

0-60 (MFX units!) in 3,2,1.... :o :D
Steve G
Danish-keyed Memotech MTX 512, CFX II and loving it
Martin A
Posts: 594
Joined: 09 Nov 2013 21:03

Re: MFX mass-storage add-on

Post by Martin A »

0 - 6 more like :)

60 would be amazing, but I don't think there's THAT many active MTX owners out there !
Last edited by Martin A on 05 Aug 2022 10:05, edited 1 time in total.
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Dave
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Re: MFX mass-storage add-on

Post by Dave »

mmm, that's a relief !

You don't have to build them :)
Martin A
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Joined: 09 Nov 2013 21:03

Re: MFX mass-storage add-on

Post by Martin A »

Dave wrote: 04 Aug 2022 17:11 mmm, that's a relief !

You don't have to build them :)
True, one prototype and 2 PCBs is more than enough for me to have built.
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Dave
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Re: MFX mass-storage add-on

Post by Dave »

The 3D printed end plates have arrived!

For comparison purposes, the photo also shows one that Martin printed on his 3D printer. His model was sent to commercial printers and I ordered up three different test pieces. The photos are not great, but hopefully show the differences, as minor as they are, between the different materials . . .

From left to right . . .

Martin's print, using black PLA
The "blackest" of the four, the slightly dappled finish is not as nice as the SLA Resin shown below, but the colour is better.

FDM(ABS)
The most expensive
The "blackest" of the three
Slightly grainy finish
Perhaps the most rigid

SLA(Resin)
The cheapest, 40% of the ABS price
Mid range colour between the ABS and SLS
Very smooth finish, pretty close to the texture of the Memotech metal end plate
Not quite as rigid as the ABS, but there’s not much in it

SLS Nylon
The mid range material, half way between the cost of the ones above
Quite coarse texture
Probably the least black one, slightly grey looking
A little more flexible than the others, but still acceptable

Although the colour is slightly greyer than I'd have liked, if I do go to this printer, then I think that the cheapest material is actually the best. The smooth texture looks the best of all three.

That leaves me with one question, should I include an end plate in the MFX price, or make it an optional extra so that folks with a 3D printer can choose to print their own, or can get one manufactured in a more exotic material from a 3D print house of their choice?

What do people think?

(I have not included costs, but in all cases, would be less that £10 for the end plate)

regards
Dave
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Update : the high res (though not necessarily high quality!) photos are available on my website here
http://primrosebank.net/computers/mtx/p ... fx-eng.htm

(Scroll to the bottom of the page)
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