English Amiga Board

Go Back   English Amiga Board > Support > support.Hardware > Hardware mods

Thread Tools
Old 03 November 2011, 00:29   #1
SpeedGeek's Avatar
Join Date: Dec 2010
Location: Wisconsin USA
Age: 57
Posts: 601
Lightbulb A3000/4000 1MB ROM Mod

A3000/4000 1MB ROM MOD REV 10

OS3.9 BB2-BB4 has outgrown the standard 512KB ROM support provided
by Fat Gary. (Standard 512KB ROM's use $F80000-FFFFFF). After a
previous attempt to modify Fat Gary's address decoding to enable ROM's
@ $F00000-F7FFFF failed a new approach to this problem was required! The problem was solved with a new GAL chip which offers the following features:

- Enables 512KB of ROM @ $E00000-E7FFFF
- Generates ROMEN and STERM signals to run a bus cycle
independent of Fat Gary!
- ROM's only enabled on READ cycles. WRITE cycles to this address
space will be terminated via STERM for faster cycle termination
- Runs a 3 or 4 clock cycle (depending on Speed jumper enable) on
STERM output to support 100 ns or 150 ns ROM's
- Runs a 5 or 6 clock cycle (depending on Speed jumper enable) on
DSTERM output to support 200 ns ROM's or overclocked motherboards!
- NEW experimental version supports 4MB of ROM @ $01000000-013FFFFF

A schematic showing the GAL chip pinout is provided. The GAL chip
must be programmed with the .jed file provided. 21 jumpers must be
connected from the GAL chip to the motherboard or optional A3K and A4K PCBs can be used. A DIP24 or PLCC28 socket is recommended to allow easy programming changes to be made. Jumpers to the motherboard should be kept as short as possible. Note: The A3000 ROM's are not connected to A19! So, you will need a jumper from Fat Gary's A19 to pin 1 of the A3000 ROM's. Enjoy!

P.S. Following Amiga tradition the name "Romy" was chosen for the new GAL Chip! Your comments are welcome!

A4000T owners should see Post #2 for A4K Romy solutions.
Attached Thumbnails
Click image for larger version

Name:	A3000_1MB_ROM.PNG
Views:	115
Size:	9.7 KB
ID:	69256   Click image for larger version

Name:	ROMY_FINAL.jpg
Views:	99
Size:	144.0 KB
ID:	69257   Click image for larger version

Name:	SUCCESS!.jpg
Views:	75
Size:	54.3 KB
ID:	69258   Click image for larger version

Name:	ARTM_E00000.PNG
Views:	73
Size:	18.1 KB
ID:	69261  
Attached Files
File Type: zip RomyRev10.zip (1.3 KB, 46 views)
File Type: zip RomyRev11.zip (1.3 KB, 42 views)

Last edited by SpeedGeek; 12 October 2020 at 22:45.
SpeedGeek is offline  
Old 05 November 2014, 16:03   #2
SpeedGeek's Avatar
Join Date: Dec 2010
Location: Wisconsin USA
Age: 57
Posts: 601

Romy Rev. 10 has been released!

Here is some revision update info:

- New state machine logic replaces counter + flip-flop logic
- REG2 was eliminated and is now a free I/O pin
- STERM and DSTERM outputs are asserted for 2 clocks to provide more reliable operation on timing modified systems
- 4MB version address range moved to $01000000-$013FFFFF


The faulty A4000T previously mentioned finally got fixed and we spent some time working on A4K Romy solutions. As I suspected, it was in fact the NCR SCSI chip kludge causing these problems!

The work around for this A4000T design bug now requires the Romy Rev. 11 GAL update attached to this post and the new P652 update found here:


NOTE: Romy Rev. 11 asserts /STERM for only 1 clock and therefore Rev. 10 is still recommended and more reliable for A3000D/T and A4000D.
Attached Thumbnails
Click image for larger version

Name:	A3K_ROMY_PCB3.png
Views:	53
Size:	26.8 KB
ID:	69269   Click image for larger version

Name:	A4K_ROMY_PCB2.png
Views:	51
Size:	25.3 KB
ID:	69270   Click image for larger version

Name:	RomyA4000_2.jpg
Views:	56
Size:	4.0 KB
ID:	69271  
Attached Files
File Type: pdf WPLCC084-T3.pdf (11.8 KB, 61 views)
File Type: zip A4K_ROMY_PCB2.zip (6.2 KB, 47 views)
File Type: zip A3K_ROMY_PCB3.zip (8.6 KB, 41 views)

Last edited by SpeedGeek; 27 October 2020 at 01:14.
SpeedGeek is offline  

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
For Sale: Elbox eFlash 4000 1MB keropi MarketPlace 2 08 May 2019 02:26
1Mb kickstart ROM in A600 possible? Turran support.Hardware 14 11 February 2013 13:28
1MB Kickstart for A4000/A3000 Turran Hardware mods 1 05 February 2013 03:58
Sale: Cyberstorm MKII A3000/4000 Dreamcatcher MarketPlace 20 13 July 2010 09:39
How to make 1MB ROM Calgor support.Hardware 26 08 August 2009 23:53

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT +2. The time now is 22:25.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Page generated in 0.07413 seconds with 14 queries