Hungarian Retrocomputer Forum - Magyar Retroszámítógép Fórum

Yo Dudes!

Just created an experimental, old school forum for retrocomputer fans. :) It is reachable on the following URL:  

http://mrf.ddns.net 

Check it out!

Sony RM 95 remote controller hack

Sony RM 95 wired remote controller has two versions:

1. REGULAR, as seen on the picture below. It has no sticker below the HOLD switch (NOR <-> ADJ). As You thought, it cannot be used to edit the EEPROM / RAM locations of various Sony devices (VCR, camcorders etc.). This seems to be the cheaper model (in 2021 it costs 40-50 EUR on ebay.de).

2. ADJUSTMENT remote controller with sticker and Sony lot number printed on it. This costs a much more (100-150 EUR!) and can be used to access the service data (edit the EEPROM etc.).

 

Fortunately I've figured out a solution how to convert a regular RM 95 to an adjustment one. Maybe there are other articles on the Internet regarding this issue, but I was unable to find it. The only reference was the RM 95 service manual and the following site:

https://english.electronica-pt.com/repair-tips?ref=RM95&marca=&sintoma=

The schematic / service manual is available here:

https://www.manualslib.com/manual/545797/Sony-Rm-95.html

But this is a description how to convert a ADJUSTMENT remote controller to a regular one! We need a vice-versa method. On the schematic it clearly seems what is missing: on a regular version R18 is not soldered to the PCB, so I've added a 10k resistor (1206 instead of 0805... :) ).

This modification was not enough to enable the adjustment mode. I have also checked J1 and J2 connections: J2 was present by default, but J1 was missing. Connecting a wire didn't solve the problem: as I thought in advance, it will either break the microcontroller or will cause malfunction. Fortunately option 2 has been realised: no damage was made to the microcontroller, but blocked the entire remote controller. So, J1 is definitively not required. :)

The solution was to short pins on the HOLD switch (as marked on PCB - see the picture below).

This step enabled the adjustment functions after switching the switch to HOLD position. Now I have a fully functional adjustment RM 95; no need for a PC software, interface, anything.

Classic 520 - 68020 accelerator board for A500/A1000

Classic 520 is not a new project; the initial tests were already completed long time ago, back in 2016. HC508 is a nice card, but the 68000 lacks one important feature: the Vector Base Register.. VBR is used in 90% of WHDLoad stuff to support the quit key. Needless to say, every WHDLoad slave can be modified to support the quit key, even on a stock 68000 CPU, but back in the days people who wrote the slaves used 68020-030 based cards and there was no need to add those extra 10 lines of assembly code to handle the quit key without a VBR feature. 

Since I can't modify hundreds of WHDLoad slaves, I've decided to design a turbo board with a 68020 CPU! :) This is how the Classic 520 was born.

Another thing is the data exchange between PC and Amiga. The CF card can be mounted and even booted in WinUAE, copying of files is easy, but this method requires powering down the Amiga, removal of the CF card etc. How much better would be a hot swap feature? And if it is already a hot swappable, then why not to use a SD card instead of CF as a data transfer media, with FAT95 filesystem?

Classic 520 can bring pleasure to Amiga 1000 owners, too. Like it's predecessor, the HC508 MK II, it is also A1000 compatible.

The final version is built on a professionally designed 2 layer PCB, fabricated at PCBWay factories in China. They did an excellent job: their website is well designed, Gerber uploading and price quotation is straightforward. The design review time frame is very short; the production started almost immediately once the order has been confirmed. Wrapping and shipping leaved nothing to be desired: the parcel arrived to the destination country in 14 days, even in a Covid situation.

Classic 520 feature list:

• 68EC020 CPU running at 28 MHz (~10x A500 speed)
• 40 pin IDE connector for HDD, CD ROM etc.
• Integrated CF card connector (bootable)
• Integrated SD card connector (FAT 16 / FAT32 compatibility for fast data exchange, hot swap)
• 8 MB Fast RAM
• 512k FlashROM for Kickstart image
• Bootmenu for controlling the system functions
• Amiga 500 and Amiga 1000 compatibility
• Better WHDLoad compatibility due to 68EC020 and VBR

The first prototype already exists: it is built on a homebrew PCB with tons of patches. The basic design had a CPU, RAM and autoconfig feature. It was enough to complete the development and debugging of the system control logic. I have used a parallel port ZIP drive as a mass storage media. It is large (100 MB per disk), but at least slow. :)

Below are the pictures of the initial prototype on a homebrew PCB: