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Commodore Amiga 2000
This is the workhorse of the series. While the A1000 introduced the world to Amiga and the A500 was the gamer edition the Amiga 2000 was expandable, high performance, high price, and had the chops for the new field of video production.
Specifications
Chips
- Agnus
- the name Agnus is derived from 'Address GeNerator UnitS' since it houses all address registers and controls memory access of the custom chips
- manages all RAM intereactions
- blitter - a sub component is responsible for
- copper - a sub component is a co-processor for
- Buster
- is the DMA arbitrary controller
- Denise
- the name Denise is a contrived contraction of Display ENabler
- Gary
- system address decoder
- Paula
- the name Paula is contrived contraction of Ports, Audio, UART and Logic, and coincidentally the chip designer's girlfriend
.
Troubles
- Blank screen, things to check
- check Agnus is seated correctly, re-seat if necessary
- swap KS ROM
- swap in CIA chips, swap one at a time
- no instant red means that the KS ROM is being read OK and the checksum has passed
- Yellow indicates
- memory issue so remove any memory expansions if present
- yellow/green can sometimes be cured by re-seating Agnus
- Gray screen
- most likely chip RAM
- Red screen
| Color | Likely Culprit | Notes |
|---|---|---|
| RED | Kickstart ROM error | Two ICs in A1200, A3000, A4000 |
| BLUE | Custom chip problem | Denise Paula Agnus |
| GREEN | RAM error | |
| YELLOW | Above problems combined | |
| LIGHT GREEN | CIA (U7/U300) problem | |
| BLACK | CIA (U7/U300) problem | If not booting |
| DARK GRAY | Hardware tested OK | |
| LIGHT GRAY | Software tested OK | |
| LIGHT GRAY | CIA (U8/U301) problem | Stops at gray, CIA defective |
| BLACK/STRIPES | ROM or CIA | |
| No video | R406 or R215 open R406=1 ohm R215=4.7 ohm | |
| Video scrambled | Agnus or Denise defective | |
Hacks
- convert A2000 OCS to ECS
- do it? nah, a fun project but little reward
- replace Agnus with a FAT(1MB) or FATTER(2MB) version
- an Agnus 8372B (found in A3000s)
- an Agnus 8375 + adapter (there are a few pinouts different from 8372)
- for gaming you only need a 1MB Agnus, there are not many games built for ECS
- for video production you need a 2MB Agnus
- Super-Denise (ECS) 8373 R4
- a drop in replacement
- 68010
- do it? yup, it's easy, non-destructive, and you get a mini boost
- the 68010 has extra instructions programmed into the CPU
- it does some fancier calculations, for instance compression
- just pull the 68000 and install the 68010
- testing will show a 5-10% improvement in performance, it so minimal that you may not see the change
- there are rumors that some programs which require a 68020 will run on a 68010, this goes back to the extra instructions in the 68010 CPU
- there may be problems with some games which can be solved by a software patch (decigel), the patch has to be loaded first
- NTSC/PAL switch
- do it? yup, it's easy, non-destructive, and allows some bitchin PAL demos
- there is a solder blob (some may have a jumper) on J102, which is grounded
- desolder that, and solder two wires to an on/off switch
- you can drilled a hole in one of the slot covers, install a small switch, then it's a reach-around to enable the NTSC/PAL mode
- if you have a Gotek drive in place, install the switch there, I like a bunch of switches and blinky lights on things
Last modified: le 2021/08/13 02:01