Matt Harlum
b2a5c3fa75
* Set slew rate to slow * SDRAM state engine: Don't wait for data strobes on reads
GottaGoFastRAMZ3 Fast RAM
256MB Autoconfig Fast RAM for the Amiga 3000/4000
Table of contents
- Status
- Features
- Ordering PCBs
- Bill of materials
- Troubleshooting
- Special Thanks and Shoutouts
- License
Status
This is tested and working in a stock Amiga 3000
If you have tested this in in another setup (accelerator etc) please let me know by opening an issue on github!
Features
128MB or 256MB Z3 Fast RAM
Brand new 64Mx16 SDRAM chips are quite expensive so the board can also be fitted with 32Mx16 chips for a much lower build cost
Ordering PCBs
I recommend ordering from JLCPCB as this board was designed within their 4-layer specifications
Recommended options when ordering:
- Thickness: 1.6mm
- Surface Finish: ENIG-RoHS
- Gold Fingers: Yes
- 45°finger chamfered: Yes
Layer sequence:
| Layer | File |
|---|---|
| L1 | GottaGoFaSDZ3-F_Cu.gbr |
| L2 | GottaGoFaSDZ3-In1_Cu.gbr |
| L3 | GottaGoFaSDZ3-In2_Cu.gbr |
| L4 | GottaGoFaSDZ3-B_Cu.gbr |
Bill of materials
| Component | Location | QTY | Link | Notes |
|---|---|---|---|---|
| 0.1uF Ceramic Capacitor, 0603 | C4-15,C17-44 | 40 | Mouser DigiKey |
|
| 10uF Ceramic Capacitor, 1206 | C2-3,C16 | 3 | Mouser DigiKey |
|
| 33 Ohm Resistor, 0603 | R1 | 1 | Mouser DigiKey |
|
| 33 Ohm Resistor network, Convex 1206 (3.2x1.6mm) | RN1-8 | 8 | Mouser DigiKey |
|
| 10K Resistor, 0603 | R2 | 1 | Mouser DigiKey |
|
| LM1117-3.3 SOT-223 | U1 | 1 | Mouser Digikey |
|
| 74LVC245N TSSOP | U2-5 | 4 | Mouser DigiKey |
Can be substituted with SN74LVTH245 or SN74LVCR2245 |
| AS4C32M16SC 32Mx16 SDRAM, TSSOP-54 | U7-10 | 4 | Mouser DigiKey |
Cheaper option is to use A3V56S40GTP for a 128MB configuration at a drastically lower price, or scavenge some 32Mx16 SDRAM from old SODIMMs* |
| Xilinx XC95144XL-10TQG100C 10ns 144 Macrocell CPLD | U6 | 1 | Mouser Digkey |
|
| Clock Oscillator, HCMOS, 7x5mm, 3.3V, ~66MHz | X1 | 1 | Mouser DigiKey |
Anything close to 66MHz should work Tested at 66.6666MHz |
* I cannot provide technical support for RAM chips other than those explicitly listed in the BOM, others may work but you're on your own
Troubleshooting
Problem: The board is detected but there is less memory detected than there should be. or you see a message stating that the board is "Defective"
Resolution:
- Check all soldering looking for bad connections and shorts around the RAM and CPLD
- Test the RAM using ATK
Look for the relevant region under "List and test regions" and test it
Consult the memory layout to determine which IC is responsible for any stuck bits you might see
Memory Layout
The memory is laid out in a way that causes it to wrap around above 128MB when only 128MB of ram is fitted to the card allowing either 128/256MB configuration with the same CPLD firmware.
Kickstart will notice this wrap and add only 128MB to the free pool in this instance.
| Address | D0-15 | D16-31 |
|---|---|---|
| 40000000-43FFFFFF | U7 | U9 |
| 44000000-47FFFFFF | U8 | U10 |
| 48000000-4BFFFFFF | U7 | U9 |
| 4C000000-4FFFFFFF | U8 | U10 |
Special Thanks and Shoutouts
- Niklas Ekström for helping to clean up my messy code
- GadgetUK164 for
being a guinea pigbeta testing many of my boards - SparxUK also for being a helpful beta tester of many of my boards
- CDH and Stefan Reinauer for helping me to get my A3000 going
- Rob "peepo" Taylor whose A500++ got me started on my journey of tinkering with Amigas
- jbilander
- RetroFletch
- SukkoPera
License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
