Phillips P2000C SASI drive

[jonb]

Well, some good news at last.

The SCSI2SD designer came back with a firmware update that latches SEL (in software - same thing it does for RES). I was wrong guessing that it already latched. I've downloaded it and now UTIL.COM is seemingly formatting the disk. Only, it appears to be stuck in some sort of loop (or maybe it is just really, really slow!). There are options for disk configuration in the CONFIG.COM program, and currently my system doesn't define a hard drive in its disk table. I'm left wondering if I should set this up prior to formatting so that UTIL.COM knows what the drive parameters are (seemingly, size up to 10 megs - OMG!!) and whether or not the drive is split into two partitions. Seems to me the formatter needs to know this.

Errm, and I can't break into it, CTRL-C is ignored. Humm.

Anyway, I have reassembled the machine so I can use the CONFIG program to specify a hard drive. It's trying to format again, let's hope it recognises the disk parameters from the CONFIG settings.... seems to be taking forever though (UTIL warns that it takes some time). Guess it's time for a cuppa tea!

[jonb]

Pow!

I'm in! And it is booting off the hard drive. Great stuff!

To get it up and running the procedure's a wee bit odd, though.

Here's what I did.
- connect scsi2sd to your PC's USB port
- Launch scsi2sd-util
- In general settings:
SEL latch enabled (not sure what it'll be called in the new config program, I don't have it yet - my firmware has it enabled by default).
Disable glitch filter enabled (makes the signal response quicker)
Startup delay 0
SCSI selection delay 0
Parity, Unit Attention, SCSI2 mode, Disk cache, SCSI Disconnect all disabled
- Device 1: scsi id 0, 10 MB, 256 byte sector
- Connect SCSI2SD to the P2000C's SASI port. Straight pin to pin (50 way edge connector to 50 way IDC) Watch the orientation!
- Power it up and boot the P2000C from a floppy
- (in CP/M now)
- launch CONFIG
- load "P2012" disk table into temporary buffer
- edit temp buffer and:
- make c: hard drive 1, 8Mb (or a 5 meg low, with d: a 5meg high)
- exit edit and save the temp buffer as "P2012HD"
- now select System Configuration and choose the P2012HD table under DISK. Alter other settings as you see fit.
- press CR to generate system. Select A as the target if it asks.
- now reboot again from floppy. You should see from the boot prompt that the extra drives are assigned.
- enter UTIL program and:
- select format hard drive
- enter 1 (to the "Which drive" prompt)
- go make some tea, it takes ages and may never stop
- when you're bored (10 mins?), reset it.
- try to STAT C:, it should report ~7800k free
- try to DIR C:, it will probably look odd.
- try to PIP c:=PIP.COM, it will probably say "no directory space"
- try to ERA C:*.*, it should work.
- now try DIR c:, it should say "no files" (this is good)
- and finally, try the PIP copy again. It should work.

To make the hard drive bootable.
- launch CONFIG and edit the P2012HD disk table
- make a: the 8MB hard disk 1
- make b: floppy 1, 640k
- make c: floppy 2, 640k
- save it again as P2012HD and generate the system on A: again (it should write to the hard drive)
- reset. The system should boot off the floppy.
- now use SYSGEN to lay down boot tracks on a: (the hard drive)
- use PIP to copy everything on b: (floppy drive 1) to a: (the hard drive)
- remove the floppy disk and reset. It should BOOT OFF THE HARD DRIVE whey hey!!

In Use
The machine is transformed. It seems very very fast indeed, just the ticket. I need to load a bunch of stuff and format the second hard drive but for now... wheee!

[leenew]

^^ and that's all there was to it surprised it took you so long to get it going
Lee.

[jonb]

Hah!

But... Bad news. Hard Disk 2 is reporting "Not Ready" in the formatter program. HD1 still OK. It will need investigating.... Might be a SCSI2SD config problem but probably something else is wrong!

(Edit: It is because SCSI2SD doesn't support multiple disks on a SCSI ID, see later post)

[1024MAK]

Hey, well done there Jon

Mark

[jonb]

Thanks, Mark! I must be getting better at this.

And if I may say so, you're definitely going to want be of these for your P2000C. Very fast.

So... At some point in the future I need to sort out some stuff:
- how to get drive 2 working (I think this is a SCSI2SD config fix)
- patch the OS so it can address more than 2 drives
- increase addressable drive capacity (current maximum is 8MB per drive or 2x5MB partitions)
- implement public user 0
- find out why UTIL.COM never completes format verification and fix

That's on top of the other P2000C stuff (reliable serial transfer, external monitor cable, floppies 3 & 4 etc, etc). All good fun!

[paulv]

That's awesome

Paul

[1024MAK]

I think you will find the maximum size is limited by CP/M. On the Memotech MTX (which also uses CP/M) this limitation is present.
However, on the MTX you can have multiple partitions. But CP/M can only use four at a time.

Modern HDDs and flash storage cards don't need low level formatting (and indeed normally just ignore a format command or do a bit of time wasting). But they do need partitioning and initialising (or reinitialization). Due to confusion in the PC world this is often still called formatting. Then the disk operating system needs copying across and the partition set up for the disk operating system.

https://en.wikipedia.org/wiki/Disk_formatting

Mark

[jonb]

@Mark: Yes, I agree. I will need to hack the CP/M driver and the formatting program to get more out of it (this'll be a major undertaking for me but it ties in with the driver work I want to do on my TRS80 Model II which is soon to have a Lo-Tech IDE interface fitted).

Fortunately the boot code should be unaffected.

Now meanwhile, I checked and it seems we can only get one hard drive out of it. The P2000C can address two drives, but they must share SCSI ID 0, and the SCSI2HD doesn't support this. I have asked if this is a permanent limitation, or whether it can be fixed. Also SCSI2SD only handles 4 targets whereas you can have up to 8 in theory, each with drives hanging off it. The way it is configured, devices can't share SCSI target IDs.

On the P2000C either drive may be up to 10Mb. Then you have the option of having a single 8Mb or 2x5Mb partitions on either drive, which you assign to any of the CP/M drive letters using the CONFIG program. So it is a litlle bit limited, but seems pretty quick to me.

[1024MAK]

From what the MTX guys say, to get CP/M to work with a larger HDD, CP/M would need to be rewritten, as the limitation is the storage and handling of the "address" used by the HDD. The system needs an extra byte for each and every area where HDD addresses are stored or used, to increase the number of "addresses". Yes, I know that LBA had not been introduced then. But you get what I mean.

I suspect that it would be hard to do this without breaking some application software.

But if you are going to give it a go, good luck

Mark

[jonb]

That's probably beyond me.

I do have a TRS-80 Model III with a LoTech IDE adapter and with Montezuma CP/M's driver I get something like 10 partitions of 10 or 8 megs each. Every one is a separate drive. That's probably the only way for now. I will have to study its code.

[jonb]

Some pictures of the installation.

The card fits nicely on the floppy drive cage behind the disk storage compartment, and it's short enough to allow enough space for micro-SD card removal and USB connection for reprogramming. I used self adhesive PCB stand-offs to attach it. The 50 way IDC edge connector opening on the P2000C's back panel is just wide enough for the ribbon to be passed into the case with the connector fitted. You do need to remove the terminal board to do this.

There is a question about where to fit a hard drive activity light. There's one on the SCSI2SD board, plus a connector, but I don't want to hack the P2000C's precious LOLPRICE RARE L@@K case. Fortunately, the floppy disk storage bay has holes moulded into it through which you can see the light from the onboard LED as long as there are no floppies in the way, so I will leave it as-is. I also considered siting a small LED behind the power light filter. This'll probably work, at the risk of getting TTL voltages a little bit close to mains voltages due to the proximity.

My SCSI2SD board is powered directly by a pair of test points (+5v / 0v) I had previously fitted to the serial board. I pass this to the SCSI2SD board via the typical hard drive Molex connector. You could also splice this into the wires powering the floppy drives, but you'd need to be careful to only connect 5v / 0v - if you were to accidentally connect the 12v line to the board's 5v input, magic smoke will certainly be released! However, mating one of the floppys' Molex plugs to it is OK, because the 12v pin is not connected on the SCSI2SD board.

[jonb]

In use it's proper quick. However...

- You need to use the latest SCSI2SD firmware with the "sticky SEL bit" feature, because the P2000C's SASI SEL pulse is so short. This isn't officially released yet (as of the time of this post).
- SCSI2SD takes more time to boot than the P2000C, so you get the "System Disk?" prompt when you first turn it on (unless there's a boot floppy in one of the drives, in which case it ignores the uninitialised SASI interface and boots from floppy).
- Only drive 1 is presently available. This maps as SASI ID 0, LUN 0.
- Drive 2 may be usable soon (SASI ID 0, LUN 1). I'm talking with the SCSI2SD designer to add the feature. Initially this will map ID 0 LUN 1 to SCSI ID 1 (which you can configure in the scsi2sdutil program).

A word on driver capability. The P2000C's hard disk driver seems to have been designed with the XEBEC S1410/A SASI - MFM bridge / controller card in mind. As a result, only two drives are supported (mentioned previously as SASI ID 0, LUNs 0 and 1). It's possible that this may be extendible to other SASI IDs; the SCSI2SD card supports up to 4 of them. I would need to hack the driver or write a new one. Also, it can address a maximum of 8MB per drive which might be too limiting. In the CONFIG utility, you have the option of either 8MB or two 5MB partitions (both of a 10Mb drive). You use the CONFIG program to assign these to individual drive letters in the typical CP/M style.

I am now going to try and sort out reliable RS232 comms so that I can start loading some software on it. Expect more cries for help in due course!

[1024MAK]

I presume it is CP/M 2.X that is being used?

On Mon, 09 Mar 2009 18:27:27 -0400, Steven Hirsch <snhi...@gmail.com>
wrote:

- hide quoted text -
>I have Googled extensively and dragged out every book on the shelf, but cannot
>find an answer to this question! Much discussion of maximum _file_ size, but
>nothing on the disk itself.
>
> From a purely mathematical standpoint, it would seem to be 1GB, but somehow I
>think the limit is lower.
>
>Steve

it's 65525*128 or 8mb in roundish numbers.

Reason they only do 16bit math and the limit is the total number of
sectors not the total number of allocation blocks.

If it were the latter it could go to 1GB. If you want that then look
at P2dos, Novados, suprbdos, Zrdos, Dosplus. Before someone else
chimes in we also had DRIs improved but those only go to 32mb
namely CP/m+ and MPM.

Allison

https://groups.google.com/forum/#!topic ... Fagrp7WT9E

Mark

[jonb]

Yes. CP/M 2.2 I believe. Comfy, like an old jumper. And likewise, a bit prickly at times!

I love it!

[jonb]

PS, isn't it about time you turned yours on?

So far I know of only five P2000Cs in the UK. Mine, yours and two that are owned by a guy on the VCF forum. Also user ChrisCwmbran has one in his collection. I think I'm the only person actively trying to use it, though..

[1024MAK]

Yes!

<embarrassment mode>
It's worse than that, I also have a new USB 'scope that I have not yet tried, a Atom from Roland that's awaiting a UK mains plug to be fitted, three Spectrum+ machines that need new membranes fitting / membranes cleaning, a Pokemon Spectrum+/128 switch keyboard that needs building, some work on a new MTX PSU, repairs to two faulty MTX boards (no make that three!), a Spectrum 128k that needs more repair work, as well as the Phillips P2000C. I'm sure I have forgotten something...
</embarrassment mode>

But real life is getting in the way...

Currently babysitting various data transfers between machines and editing various files (alas automating would take just as much time as I'm trying to sort relevant files into a properly named folder structure ) while waiting for the PV Solar guys to come back and commission my new installation (they finished the electrics after sunset yesterday).

Still, it's all fun and games, gotta go, a file transfer has just finished...

Mark

[jonb]

One more update.

I now have an updated firmware that gives access to both hard drives, so my P2000C has A: (HDD boot drive), B & C (floppies) and D & E (HDD 5MB drives) all working nicely. It's the best possible outcome. I am sure that there will be a release of this firmware soon, and an updated configuration program with new options:

- SEL sticky bit option, required when your SEL pulse is too short
- "SASI ID 0, LUN1 mapped to device 1" option which enables dual drives on a single SASI ID

These are needed to get it working on the P2000C.

[etaoin]

A small addition to prevent someone going on a wild debug-goose chase like me:

If you wire up 1-to-1, pin 32 on the scsi end (/ATN) will end up connected to ground on the P2000C side. I'm using the DIY scsi2sd from eltradec.eu with firmware 4.8, and that prioritizes /ATN over /REQ/ACK. Just disconnect pin 32 and pull up /ATN on the scsi2sd side and it will work fine.

[julians]

So far I know of only five P2000Cs in the UK. Mine, yours and two that are owned by a guy on the VCF forum. Also user ChrisCwmbran has one in his collection. I think I'm the only person actively trying to use it, though..

Plus mine and one other I know of.
Will add it to my big list of things I ought to do something with as I'm sure I've also got the 8088 co- processor card somewhere too...

Julian.