Interface 1 LAN

For experts to discuss very technical stuff and newbies to ask why the Spectrum they bought off ebay doesn't work.
Post Reply
User avatar
jpnz
Berk
Posts: 35
Joined: Tue Nov 14, 2017 4:07 pm
Location: Hamilt[r]on - City Of The Future - NZ

Interface 1 LAN

Post by jpnz » Sat Nov 02, 2019 9:29 pm

This has been on my list of things to do for quite some time now and I've finally stood up a simple Interface 1 network:

Image

The setup consists of a toast-rack and a Spectrum+ (with composite mod) both fitted with an IF1 v2 linked together.

In the middle is a vDrive connected to the Spectrum+

I wanted to know if the LAN worked, if it was any good and could I get transfers to be audible

Bruce Lee seems to be flavour of the month so have been using that for testing.

Testing is a client/server scenario - the game and a BASIC bootstrap are loaded from the vDrive on the Spectrum+

The toast-rack is configured to load via a network broadcast and a key-press on the Spectrum+ initiates the transfer of the bootstrap and game

Does it work? Is it audible?



Yup!

I'll be posting some more about the topic later on
6 x

User avatar
Ast A. Moore
Dynamite Dan
Posts: 1189
Joined: Mon Nov 13, 2017 3:16 pm

Re: Interface 1 LAN

Post by Ast A. Moore » Sat Nov 02, 2019 10:11 pm

Excellent! Your Toastrack needs a simple mod to eliminate (well, greatly reduce) the alternating dark and bright vertical bars. I did it to mine and tamed them down noticeably:

Image

What I did was the following:

1. Replaced C28 on the ULA’s 5V rail with a 47 µF capacitor (the original was 22 µF, and still measured fine; didn’t measure the ESR, though).
2. Replaced C25 in the resistor/diode logic that mixes the brightness signal with RGB before feeding the into the TEA2000 with the same value (100 µF). Probably unnecessary, but it sits close to the ULA and the color signal tracks. The original capacitor measures fine, so I might put it back in.
3. Replaced C8 and C7 22 nF ceramic decoupling capacitors next to RAM IC13 and IC12, respectively, with 1 µF multilayer ceramic ones.
4 x
Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.

User avatar
jpnz
Berk
Posts: 35
Joined: Tue Nov 14, 2017 4:07 pm
Location: Hamilt[r]on - City Of The Future - NZ

Re: Interface 1 LAN

Post by jpnz » Sun Nov 03, 2019 1:09 am

Ast A. Moore wrote:
Sat Nov 02, 2019 10:11 pm
Excellent! Your Toastrack needs a simple mod to eliminate (well, greatly reduce) the alternating dark and bright vertical bars...
Thanks for the tip, the display looks really clean. Not that simple for me, so will put that on the list of things to do...
0 x

User avatar
jpnz
Berk
Posts: 35
Joined: Tue Nov 14, 2017 4:07 pm
Location: Hamilt[r]on - City Of The Future - NZ

Re: Interface 1 LAN

Post by jpnz » Sun Nov 03, 2019 1:41 am

jpnz wrote:
Sat Nov 02, 2019 9:29 pm
...I'll be posting some more about the topic later on...
I'd been reading about the LAN speed in a couple of books,

Andrew Pennell writes in Master Your ZX Microdrive:
Networking is a method by which many computers can be linked together so that they communicate quickly between each other.
On the Spectrum this speed is over 3K bytes per second, which is much faster than the greatest RS232 baud rate of 19200.
However, Dr. Ian Logan observes in [the] Spectrum Microdrive Book:
The Spectrum Local Area Network (just network from now on) allows for a number of Spectrums (and computers of other makes) to be joined so that 'high speed' communications can be made from one Station to another. The rate at which data is sent over the network is indeed fast, as compared to a RS232 link, and may nominally be considered to be 5K bytes/second (each byte having 8 bits).
[Station - a computer presently joined to the network]

He further notes:
A program sent as a 'broadcast' is handled at a much slower rate (about four times slower) than a program sent to a specific IRIS
[IRIS - the station with which the user is communicating]

My previous test was a broadcast so I wondered if a station to station session was indeed faster?



Yup!
3 x

zxbruno
Dizzy
Posts: 75
Joined: Sun Mar 04, 2018 6:13 am

Re: Interface 1 LAN

Post by zxbruno » Sun Nov 03, 2019 7:05 am

Always wanted to see this in action!

Things I'd like to see one day:

-A Battleship-kind game, where each player has his own Spectrum and display
-Turn-based games, where each player has his own Spectrum and display
-2-player games, where the game runs on one Spectrum and one display, and the second Spectrum is only used as a keyboard to control the second character. Beat-em-ups come to mind
-A Spectrum playing chess against another Spectrum
2 x

User avatar
jpnz
Berk
Posts: 35
Joined: Tue Nov 14, 2017 4:07 pm
Location: Hamilt[r]on - City Of The Future - NZ

Re: Interface 1 LAN

Post by jpnz » Sun Nov 03, 2019 8:13 am

zxbruno wrote:
Sun Nov 03, 2019 7:05 am
Always wanted to see this in action!

Things I'd like to see one day:

-A Battleship-kind game, where each player has his own Spectrum and display
-Turn-based games, where each player has his own Spectrum and display
-2-player games, where the game runs on one Spectrum and one display, and the second Spectrum is only used as a keyboard to control the second character. Beat-em-ups come to mind
-A Spectrum playing chess against another Spectrum
Hehe, yeah - me too!

There are some existing games that support the IF1 LAN but I really didn't get a chance to test them out

[EDIT] - corrected my badly linked URL :/
0 x

User avatar
8BitAG
Manic Miner
Posts: 315
Joined: Sun Dec 17, 2017 9:25 pm

Re: Interface 1 LAN

Post by 8BitAG » Sun Nov 03, 2019 9:17 am

When I first went to my local comprehensive school, while I was still at primary school, they had a whole room full of networked Spectrums (and maybe even some QLs), all mounted on wood with the wires threading around the room... at least, that's what I presume the setup was as sadly it was replaced by a suite of BBC Masters before I enrolled.
1 x

User avatar
jpnz
Berk
Posts: 35
Joined: Tue Nov 14, 2017 4:07 pm
Location: Hamilt[r]on - City Of The Future - NZ

Re: Interface 1 LAN

Post by jpnz » Sat Nov 09, 2019 9:51 pm

Thanks for all the comments.

I wanted to add a few more notes about the setup

I got the LAN cable from RWAP Software in either 2007 or 2008 and that's an indicator of how long I've been meaning to do this!

I'm unsure if the cables are still available, but the regular Sinclair cassette leads (with the black/grey sleeves) should also work.

One quirk I did see, especially when broadcasting, was a number of CODE error(s) generated by the IF1:

Image

This tended to happen when the toast-rack was sending or receiving in it's native 128K mode.

These errors were mitigated by switching the toast-rack to 48 BASIC via the menu option, or via USR 0.

As for the game, it's a Hrust2 compressed version of the Erbe release of Bruce Lee, with MAC's new loading screen on a microdrive cartridge.

I was also able take a Multiface snapshot to microdrive of the toast-rack after it had received a station to station transmission (but not a broadcast) so the system variables can be inspected at a later date.

Both microdrive images I used for testing are here
1 x

Post Reply