SF500

SF500

Spitfire 500, A low-end 14 MHz Accelerator with IDE and 4/8 MB fast RAM for the Amiga 500.

Heavily inspired by Matthias Heinrichs' CDTV-RAM-IDE board. Many thanks to Matze for sharing his work and letting me open source this project.

https://gitlab.com/MHeinrichs/CDTV-RAM-IDE/

Please note, if you are going to build boards and sell for profit, you will need a consent from Matthias and also from Oliver Kastl if you are going to bundle this software http://aminet.net/package/disk/misc/oktapus with the hardware (ROM-chip).

Board is four layers:

signal (with 3V3-zone)
power plane (GND)
power plane (VCC)
signal

Rev. 1B installed in an A500. The 7/14 MHz switch can be easily accessed if hanging out the sidecar port opening of the A500 case. This switch can also be switched while the machine is running.

Videos:

https://drive.google.com/file/d/1c2K9_kcEqxMMBJBd1aELfbt1fV5XXoU6/view?usp=sharing

SysInfo tests running oktagon.device on WB 1.3 on KS 1.3:
https://drive.google.com/file/d/1rewl8bivpIMPoLze_-Y7_mGYqzTiX6ET/view?usp=sharing

Cold boot running oktagon.device and WB 1.3 on KS 1.3:
https://drive.google.com/file/d/1MFdxnaCo8lNMqMQ6eJMtNUMSsBB8mtb-/view?usp=sharing

Cold boot running scsi.device v109.3 (oktapussy) and ClassicWB 3.1 (with 1.3 theme) on KS 3.1:
https://drive.google.com/file/d/1IrmWWG6SJgc65BBj8jGnHebKbp6LAcYa/view?usp=sharing

The CPU and the speed-select switch clears the A500 keyboard nicely when installed. Also the CF- or SD-card adapter clears the ROM-chip nicely.

Performance

14 MHz and JP3 Open (scsi.device v109.3):

14 MHz and JP3 Closed (oktagon.device v6.10):

Keep in mind Kickstart 1.3 does not have FFS (Fast File System) in ROM, so in order to use FFS with 1.3 make a small boot-partition (e.g. ~200 MB) and format it DOS\1, not International (DOS\3) or DirCache (DOS\5), and not OFS (DOS\0). For KS 3.1 I would format it FFS International (DOS\3) or perhaps use PFS3.

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

Also, do not forget to set the MaxTransfer to 0x1fe00 and hit Enter button after typing, then save the setting. This applies to all versions except the new KS 3.2

How to Build:

The ROM image to burn to the AM29F040B-70JC chip can be downloaded from here:
https://gitlab.com/MHeinrichs/CDTV-RAM-IDE/-/blob/master/Prog/ATOKTACOMBINED.rom-512.bin

The 64 KB ROM under Releases is a combined ROM I made with the instructions from the textfile EPROM-Hack_english.txt in this repo (also available in German). It is 060-compatible too, not that it makes any difference for this accelerator that uses a 68000 or 68010 CPU.

Burning any of the two ROM:s above will work with this Accelerator (SF500).

The last version of the Oktagon2008 from BSC is 6.12 - but still reports as 6.10. As far as I know, only the boot code has changed to be compatible with the 68060. The actual driver is still 6.10.

Remember to Program the chip BEFORE you solder it down to the PCB. Do not byteswap if you are using a TL866II-Plus or similar programmer on Windows/Intel-arch, these parts are 8-bit so there is no concept of byte swapping.

Soldering: Start with all the surface mounts and then TH. I usually start with the Voltage regulator and verify the 3V3. Then the CPLD and verify JTAG-connection, doing a boundary scan with ISE-Impact. No need to solder a pin header to the JTAG connector on the PCB, just hold the connector in position and press gently. It should also be possible to use a Raspberry Pi and the program xc3sprog. Optionally you can put 10k or 4.7k pull-ups on R10-R12 (TMS,TDI,TCK) if you have problems connecting to the CPLD, those are 3V3 pull-ups so shouldn't damage anything using GPIO from a RPi. VCC is +5V and can be supplied through a typical usb phone-charger or similar, check polarity BEFORE you plug it in.

Using some kapton tape can help to hold the chip in place while tacking it down to get everything aligned properly. For the ROM-chip I pre-tin the pads and then use hot air rework station to solder it in place.

When all the surface mount components are done it's time for the TH-pins. I use an old 68k CPU as a jig and a piece of pin strip on the other side to align the pins while soldering them in position. Press ontop the CPU somewhat at the same time when soldering for a great result.

I used a 1.2mm thick PCB as a spacer while soldering the 44-pin IDE connector in place. This because it'll clear the Kickstart ROM chip better if the connector and hence the adapter is positioned a little higher up. The 44-pinout on the PCB is deliberately flipped/designed so that you can plug the CF or SD-adapter directly to the angled-connector the "right" way, no ribbon cable and no buffering is used.

The final result. The mini-slide switch can optionally be soldered directly to the PCB if you prefer it that way. Only two pins are actually used, it's a normal two pin jumper with default pull-up, the third pin/hole is not connected and is only there to allow for soldering the mini-slide switch directly onto the PCB.

Programming can now be done either this way...

...or like in picture below...it requires the Amiga PSU to be turned ON to provide +5V to the Accelerator, do not connect any external +5V here:

Jumpers:

/CFGIN = This jumper is to activate autoconfig (active low with 1k pull-down resistor R3). No jumper here means no RAM nor IDE will be autoconfigured. 
SW1 = CPU speed toggle between 7 or 14 MHz, default 10k pull-up means 14 MHz
JP2 = Selects between 4 or 8 MB fast ram autoconfig, 8 MB requires U7,U8 populated too.
JP3 = Selects between IDE driver oktagon.device or scsi.device_v109.3 (oktapussy)
JP4 = Selects between Autoboot or Not, jumper Closed means autoconfigure will not load the ROM-vector (the JP3-selected driver).

Synthesis Summary:

Zipped JED-file (main_top.jed) available under Releases

New firmware released 2021-12-22 that supports DMA from A590, available under Releases

SF500 and A590

With the updated firmware it's now possible to use an A590 (on the A500 expansion edge) togheter with a SF500.
You will need to solder/connect a jumper-wire from the CFGOUT-goldfinger-pad and run it to the CFGIN-pin on the SF500. This will asure that there will be no conflict during AutoConfig cycles. They will be daisy-chained meaning the A590 configures first and the SF500 is second in line.

Having the A590 jumper set to enable onboard memory (2MB in picures below) is not optimal in this case since that memory will automatically be used first by the system. You will have to set the jumper (JP2) to ON (4MB) on the SF500 in this scenario but as you can see only 0.84 mips here:

In this case it's much better to set the A590 jumper to Amnesia and hence "only" use the 4MB or 8MB from the SF500. Don't worry the A590 can then DMA (Direct Memory Access) into that memory:

With the SF500 set to Amnesia we get the full performance at 14 MHz and we can use the Hard Drive in the A590 either to boot from or just as a second harddrive for storage or backup (this depends on boot prio setting). Both the Oktagon.device and the Oktapussy scsi.device can co-exist with the A590 driver. As you can see the oktapussy driver takes the name 2nd scsi device here:

Changing boot priority in HDToolBox let us select which drive to boot from. Please note, I used prio 10 here but if you still want the DF0 floppy drive as the first device (you probably will) then you can't put in a number above 5. Keep it below 5 since DF0 has boot priority 5 by default, this was just for testing, remember to press Enter after entering the new value in the box and then hit the Save Changes to Drive button before you do a reboot.

A short video showing boot from A590 in Amnesia mode and copying a 2.2 MB file from the SF500 IDE drive to the A590 XT drive.

https://drive.google.com/file/d/1oLW0H9GmMaRv7rbYKLQVwRg4RvrDyU3E/view?usp=sharing

Here a short video booting from the SF500 IDE drive (with higher boot prio set) than the A590 (still in Amnesia mode). The A590 harddrive is automatically mounted and available to the system after startup:

https://drive.google.com/file/d/13qs9DawRrVdHNif9vCZlh3xlq8YgDj_f/view?usp=sharing

BOM Rev. 1B

Happy Hackin'

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