CD-ROM, SCSI or IDE?

[Marchie]

I need to install a CD-ROM into an A2000:

I already have a SCSI card with a HDD on-board and a spare socket at the back, is that the best way to connect a CD-ROM? Are there different types of SCSI I need to worry about (8-bit vs 16-bit?)

I suppose it's too much to hope I can just take an IDE drive from an old PC and plug it in?

[Matt_H]

Any SCSI CD drive should work. Just about all internal drives are 50pin, like your hard drive. If you're connecting externally, you'll need the appropriate cables. Common "vintage" external drives use a Centronics connector, newer ones use HDC50 or 68 pin cables. Assuming your external SCSI port is an DB25 pin connector (as most Amiga external SCSI connectors are) all you need is a simple cable with the right connectors at both ends. If the drive has a 68 pin connector, you need an additional adapter.

Adapters to connect IDE drives to SCSI systems exist, but they are very expensive.

[Marchie]

Thanks Matt H, that's all really helpful!

[dirkies]

Wouldn't IDE activity tax the CPU more compared to SCSI (and moreover be slower)?

[Kin Hell]

Originally Posted by dirkies

Wouldn't IDE activity tax the CPU more compared to SCSI (and moreover be slower)?

[pandy71]

Originally Posted by dirkies

Wouldn't IDE activity tax the CPU more compared to SCSI (and moreover be slower)?

It will use less CPU only if SCSI perform DMA transfers - AFAIK there is no IDE for Amiga with DMA (quite strange).

[Zetr0]

@Pandy71

There is only 1 IDE DMA based Card for the Z2 Amiga and that is the Masoboshi MasterCard 702+

Its pretty impressive once set up - sadly it is a lot like the GVP method of DMA into the on board 16bit Memory - This means if you are using a CPU upgrade it will have to shuffle it about - a slight performance hit - but an 030@40 can achieve about 2MB per second - with a 40% cycle hit.

Here is the GVP SCSI tested for transfer speed and CPU usage - (stock 68000 CPU @7.4 MHz - 8MB FAST Z2)


The Masoboshi master card is very similar in output - I will see if I can dig up an image for that one

@Marchie
Well worth investing in if you want a good IDE solution (that is NSD compatible i.e. >4GB ) with your Z2 equipped Amiga - If memory serves you are limited to 1 device on the IDE bus - although I never got to round to confirming that - had 4 on the SCSI at the same time though - so that was fun - it was a very handy solution to writing basic workbench partitions on SCSI from a WinUAE set up IDE hard-disk =)

I would suggest a SCSI Optical Drive as that is the cheapest option - however I would advise that you avoid Apple SCSI ROM's as some of these are butchered so as not to be able to read CDDA and Mix-Mode CDROM's - Apples Lovely White Picket Fences!

Alternatively you could look at a SCSI-IDE bridge - there are a few out there that take an IDE Optical Drive and convert it to SCSI - I have one of these running an IDE DVDRW on my A2000 via SCSI - plan on making a dual Drive Bay with two SFF IDE Optical Drives - but we shall see - busyness seems to be a tad prevalent over the last few weeks.

[Toni Wilen]

Thats the only IDE DMA controller, for some strange reason.

There isn't many Z2 SCSI DMA controllers either, Commodore A2091 and GVP Series II boards (and Masoboshi) are the only ones. The rest are PIO.

Technically A2090 (and very rare Supradrive 2000 DMA) are DMA too but their DMA implementations aren't that good..

Note that (Z2) DMA is not always the fastest choice, most accelerators come with 32-bit RAM outside of Z2 address space: controller stops working or it becomes slower than any sane PIO controller. (sane = CPU only needs to do data transfers, hardware does SCSI data transfer handshake automatically and transparently. "fake/pseudo DMA"). "Correct" solution is to get accelerator that has built-in DMA SCSI controller

[pandy71]

Yep, i think most of solutions are based more or less on Commodore DMAC or very similar approach as such they support only 24 bit addressing - technically there is no limitations for IDE - in fact sometime it may be faster than SCSI especially if SCSI is limited to 20/40MBps but... from strange reason IDE DMA was accordingly to Zetr0 implemented only in single product and now i think is too late to even try to do such things... if any then probably is better to focus on some DMA SD controller (imagine RAID on 8 SD cards ).

[Toni Wilen]

It is not directly DMAC limit, Z2 bus has only 24 address bits.

[Zetr0]

If memory serves, for true SCSI DMA combined with a CPU upgrade - for the A2000 that would be the following adaptors

Blizzard 2040 (ERC)/2060 - Fast SCSI 2
40/4 Magnum (68040@25/33MHz) Fast SCSI 2
TekMagic 2040/60 Fast SCSI 2
Wild Fire (one day I will get to cuddle one) - It even has DMA 100Mbit Ethernet!!

Now, a couple of interesting boards to mention are the GVP Combo / G-Force series - While they claim DMA, I found it substantially slower in comparison to say a Blizzard with the same SCSI controller - From my tests with the GVP Combi 030@50MHz and the G-Force 040@33MHz - the latter in burst mode, score about the same - 2MB per second. However CPU cycle wise they both get hammered with over 50% of cycles used for the 040 and 030 more so- I suspect this is not TRUE DMA, but instead most likely a FIFO buffer strategy based on the Impact Series 2 Chip that they (GVP) put with a lot of other 16bit SCSI Z2 Adaptors.

[Zetr0]

Originally Posted by pandy71

Yep, i think most of solutions are based more or less on Commodore DMAC or very similar approach as such they support only 24 bit addressing - technically there is no limitations for IDE - in fact sometime it may be faster than SCSI especially if SCSI is limited to 20/40MBps but... from strange reason IDE DMA was accordingly to Zetr0 implemented only in single product and now i think is too late to even try to do such things... if any then probably is better to focus on some DMA SD controller (imagine RAID on 8 SD cards ).

I have to admit my good friend, I really am not sold on the serial (8bit) SD (Secure Digital) technology in regards to DMA mass storage for the Amiga. If I was going to wave a magic wand and create a 32 / 64 bit DMA controller for the Amiga it would probably be Serial ATA based - its a wider bus / bandwidth than SD and there is a lot more support out there for this format - from optical drives, solidstate and even the classic spinning media .

[Toni Wilen]

Originally Posted by Zetr0

Wild Fire (one day I will get to cuddle one)

Wild Fire does not really exist in my opinion but if you find one, dump the ROM first

40/4 Magnum (68040@25/33MHz) Fast SCSI 2

This is not yet emulated (I don't have boot rom dump) but it is guaranteed to have DMA SCSI because 53C710 has built-in DMA controller.

Now, a couple of interesting boards to mention are the GVP Combo / G-Force series - While they claim DMA, I found it substantially slower in comparison to say a Blizzard with the same SCSI controller - From my tests with the

Same controller? Blizzards had much newer ESP/53C94/FAS216 type controller chips and GVPs always had "old" WD33C93.

Or what did you mean by same controller?

GVP Combi 030@50MHz and the G-Force 040@33MHz - the latter in burst mode, score about the same - 2MB per second. However CPU cycle wise they both get hammered with 50% of cycles used for the 040 and 030 more so- I suspect this is not TRUE DMA, but instead most likely a FIFO buffer strategy based on the Impact Series 2 Chip that they (GVP) put with a lot of other 16bit SCSI Z2 Adaptors.

Combo 030 (and A530 which is more or less same hardware) is emulated and SCSI emulation does use GVP DMA hardware. (NetBSD driver also uses DMA, not CPU copy loops). Both also have GVP DMAC chip (GVP-DPRC-01).

[mark_k]

I remember reading somewhere that SCSI DMA on GVP accelerators is slower than with GVP Zorro II SCSI boards for some reason.

[Marchie]

Originally Posted by Zetr0

@Marchie
Well worth investing in if you want a good IDE solution (that is NSD compatible i.e. >4GB ) with your Z2 equipped Amiga - If memory serves you are limited to 1 device on the IDE bus - although I never got to round to confirming that - had 4 on the SCSI at the same time though - so that was fun - it was a very handy solution to writing basic workbench partitions on SCSI from a WinUAE set up IDE hard-disk =)

I would suggest a SCSI Optical Drive as that is the cheapest option - however I would advise that you avoid Apple SCSI ROM's as some of these are butchered so as not to be able to read CDDA and Mix-Mode CDROM's - Apples Lovely White Picket Fences!

Thanks Zetr0, I'll go for a SCSI Optical drive.

Out of interest, once one has an external enclosure, is it possible to put a CD/DVD writer in there? Or does the software not exist to burn optical discs?

I'm looking for ways to port animation/video data from the Amiga to my PC, but ethernet cards seem to be rare and expensive...

[Zetr0]

@Marchie

My friend, a good call, now have a look on www.aminet.net for "MakeCD" - I used to use this "back in the day" to Rip.. *cough* ... *ahem*... errr back up CD Games from PC via my Amiga.

While I was able to read DVD disks via the Amiga (using AmiCDFS) I don't ever remember writing to a DVD via an Amiga.


@Toni

Originally Posted by Toni Wilen

Same controller? Blizzards had much newer ESP/53C94/FAS216 type controller chips and GVPs always had "old" WD33C93.

Or what did you mean by same controller?

Sorry my friend, I should of been clearer - both the GVP Combi 030 and G-Force 040 use the GVP SCSI interpretation found on GVP Impact Series II SCSI Cards. Hence I suspect the 16bit SCSI Data is transferred using a FIFO buffer as opposed to real DMA compared to the Blizzard 2040/60 or even GVP's TekMagic 2040/060

I could be wrong, but the results I have seen tend to suggest it however.