Joystick Port

Champion (336)

28-03-2019, 23:40

Pins 6 and 7 are not exactly bidirectional, as the 367 can drive the pins 6,7 both low and HIGH. It can float high by changing state of G1 input but it is not the same as MSX which uses open collector outputs (ls07s) on pins 6,7 of both joystick connectors.
btw, interesting site with schematics and a project to bitbang RS232 in and out the joystick port. I have did transmission up to 31250bps but never tested my receiving routines.

Par gdx

Enlighted (6219)

29-03-2019, 09:18

Pentarou wrote:

I found out that the MSX Joystick standard is not original but copied from the パピコン (PC-6001 1981), so the MSX-HID should be named NEC's HID

No, because this port is a standard used in Japan at the time for many computers. It is based on the port from Atari 2600/VCS. It has only been a bit improved.

Par Pentarou

Hero (523)

29-03-2019, 15:05

Danjovic wrote:

Pins 6 and 7 are not exactly bidirectional, as the 367 can drive the pins 6,7 both low and HIGH.

Well, Joy 1 and 2 aren't independent, but pins 6 and 7 can do both input and output, so they are bidirectional.

gdx wrote:

No, because this port is a standard used in Japan at the time for many computers. It is based on the port from Atari 2600/VCS. It has only been a bit improved.

What do you mean? It's obvious that the joystick port has been created by Atari for the VCS (1977) and their old home computers (1979), almost every machine that came after that followed the standard and sometimes improved it (NOT only Japanese machines).
But the MSX and other Japanese computers seem to share some common traits: For example they ditched the paddle support, have GND on pin 9, pin 8 is an output and there are 2 triggers.
So there seems to be a de-facto/quasi standard, the first machines to use it were NEC's while the MSX just copied it (and according to Danjovic, improved it a bit ).

Par gdx

Enlighted (6219)

29-03-2019, 15:22

I say several Japanese computers use exactly the same port (MSX included). The PC-6001 is probably the first.
The goal of the MSX standard at start was to use already widespread components.

Par Pentarou

Hero (523)

29-03-2019, 15:46

And Commodore, Spectravideo, COLECO, Amstrad did the same in the west. So? What do you mean?
PC-6001 established a standard and MSX copied it in full.
Other Japanese computers have little differences, for example Sharp X1 didn't have VCC, X68000 have only 1 bidirectional Joystick port, FM TOWNS has pin 6,7 and 8 as bi-directional, NEC PC-8801mkIISR has bi-directionality also on pins 1-4, MZ-800 has pin 7 as input only.

Edit: Sorry, after I posted the reply above I noticed that you edited your post... My reply was aimed at what you posted before.

gdx wrote:

The goal of the MSX standard at start was to use already widespread components.

I only wanted to say: What is believed to be unique to MSX was copied from NEC.

Par Danjovic

Champion (336)

29-03-2019, 15:57

I have expressed myself poorly....sorry!
What I had in mind is that the pins can not float independently like in MSX. Such capability (to float independently) provides more flexibility for instance MSX can use solely 2 pins to do I2C.

Par gdx

Enlighted (6219)

29-03-2019, 16:23

You forgot to say that the pin 8 status of the FM-TOWNS is different by default. Yes there are slight variations but they are compatible for most functions. MSX and PC-6001 ports are managed by the same chip (the PSG) so there is not much alternative to do different while remaining compatible for main functions.

Par TomH

Champion (366)

29-03-2019, 20:31

If I dare: I think that what's being called the MSX HID here is supposed to be analogous to the USB HID. It's the protocol, not the wiring. So it's the three-byte means by which joysticks, mice, trackballs, lightguns, paddles and dual-axis analogue controllers can be identified, and the manner by which they surface data subsequently. With Sega also having implemented a compatible series of three-byte signatures for its Mega Drive and Saturn.

That the physical port is very close to the Atari 2600's, and therefore to a lot of other machines, isn't really the argument — especially given that Saturn devices are considered to be MSX HID compliant, but have a completely different physical connector.

(EDIT: they also have really nice joypads; is a passive adaptor available?)

Par Danjovic

Champion (336)

29-03-2019, 23:44

TomH wrote:

... is a passive adaptor available?)

By passive you mean without extra hardware? If so it is possible to connect the Saturn joypad directly to the MSX joystick port and get the button data by changing the state of pins 6/7. Of course some software will be required....

Par sd_snatcher

Prophet (3659)

30-03-2019, 05:00

Yep, TomH is correct: MSX-HID is a protocol, not the port. This is why it's on a separate article from the General Purpose Ports. Both the Mega Drive and Saturn have different connector pinouts, but use the same protocol.

You can connect whatever you want to the General Purpose Ports, but if it's not MSX-HID compliant you won't have the benefit of auto-detection, and it will probably conflict with existing MSX-HID devices.

In that article, I even listed some existing devices that are not compliant.