Mainframe Computers in Shadowrun

The only mention of pricing or functionality for mainframe computers in Shadowrun is in the VR 2.0 rules, and that is frankly silly. They suggest that a mainframe should cost 5 million Nuyen per Security Value point. This doesn’t account for the obvious fact that a Red-8 system should be vastly more expensive than a Blue-8 system. It also means that mainframes would be amazingly lucrative targets for runners (or perhaps that for some magical reason the kind of power described as a mainframe is actually astronomically larger than any of us in our gaming group (most of whom are engineers) can believe, such that a mainframe would be so large as to be nonportable even to a troll).

So here is the system we worked out. Here are a couple of the other goals and criteria we had:

It turned out that after we sat down and wrote some more detailed statements about what should come out of the desired system, it was obvious to the mathematicians in the group that not only could we meet them all but that doing so gave an obvious simplest result. Here it is:
Basic Rating/Capacity System
Quality Rating Cost Capacity Range Cost per
Capacity Point
(per card)
Standard 1-3 100,000¥ × Rating2 1-180 5000¥ 5
Alpha 4-6 250,000¥ × Rating2 181-720 12,500¥ 10
Beta 7-9 500,000¥ × Rating2 721-1620 25,000¥ 20
Delta 10+ 1 M¥ × Rating2 1621+ 50,000¥ 40

The capacity of a mainframe is measured in system capacity (SC), the basic unit for the remainder of this system. For any mainframe, it is 20 times the rating2, though a mainframe can be configured to any arbitrary number of system capacity points.

System components have different quality levels; we’ve used ratings similar to cyberware to give an appropriate feel for the levels of quality. The given tiers of mainframe are the ones that require a given quality level of components in order to keep the system from bogging down. In theory, you could use standard components to put enough capacity in one place to make a Rating 10 mainframe, but the components would be unable to correlate with each other fast enough, and the system would crash frequently from routine operations. Since higher-quality components are smaller and faster, you could always build a low-rating mainframe out of higher quality components, which would generally result in a smaller machine.

Mainframes generally take the form of a chassis with a power supply and a rack inside that can hold cards (about the size of a modern PC motherboard) that contain a given amount of processing hardware or interfaces to other systems. A Rating 1 mainframe is no larger than a desktop computer of 1996; larger ones are the size of a refrigerator. Higher-quality components are smaller, faster, and fit more on a card, so it’s possible to make a mainframe smaller by building it out of components that are of a higher quality than necessary for a system. You can get 5 Standard points on a single card; 10 Alpha grade components will fit in the same space, or 20 Beta grade, or 40 Delta grade. (Yes, for 2.5M¥ you can fit a 900,000¥ rating 3 mainframe into a rating 2 chassis by making it out of Beta and Delta grade components; it also means that a Rating 7 mainframe occupies about as much space as a rating 5 or a rating 10.) Machines containing the more expensive cards often have elaborate security systems to prevent someone from making off with 2M¥ worth of components in a briefcase.

Spending System Capacity

Color Multiplier

Almost everything you spend system capacity on has its cost multiplied by a number based on the Security Code. This multiplier represents the amount of overhead the host is using to ensure that programs are running safely.

Color Multiplier (CM)
Blue 1

System Infrastructure

The capacity cost for the actual operating system and other infrastructure is computed as follows:

Normal Things

Operating System and Security Infrastructure On a Blue or Green system, (Security Value) × CM
On an Orange or Red system, (Security Value)2 × CM
Cost Per Simultaneous User 1 × CM
Apps that could run on a PC built into the cost per user
Mainframe Applications 1 × CM per Gpulse of data manipulated
“Offline” Storage 1 × CM per Terapulse (1000 Gpulses)
“Indexed” Storage 1 × CM per 10 Gpulses
“Active” Storage 1 × CM per 1 Gpulse
Connections (LTG, etc.) 1 × CM per connection
Slave functions 1 × CM per reasonably-sized group of identical slaves (e.g. one building’s elevators, all the capacitance detectors on the perimeter fence, etc.)


Unusual Things

As mentioned above, putting something in the wrong subsystem costs three times as much as normal. There are some other special cases mentioned in VR 2.0 that this doesn’t cover:

Subsystem Ratings

At first these seemed problematic, but then we realized that these are inflated to give the right ranges of target numbers.

Using a Mainframe to Write Cyberdeck Programs

(This is the other replacement for text in VR 2.0. It retains the flavor and nature of the VR 2.0 rule but has numbers for this system.)

To use a system in developing cyberdeck programs, the system must be running a Security Code of at least Green. The maximum rating of program that can be developed is equal to the Security Value. Program development requires 1Gp per 10 Mp of the program’s design size. The 300,000¥ mainframe programming suite, if present, takes 8 Gp. (As usual for a mainframe app, the size in Gp times the CM gives the capacity cost for running the app.) See the example systems for an example of this.

What about all those little shops with Orange security?

Most of the shops in Sprawl Sites that have impressive security are just leasing space on someone’s mainframe— possibly even a small virtual machine— but certainly don’t actually have Orange systems in the shop waiting to be stolen.

Example Systems

System One: Rating 1 (100,000K¥)

This is a system for a small business. It has 20 capacity points, runs at Blue-4/8/8/8/8/8, has 1 PLTG connection, 1Gp business data & software, and a total of 14 users + slave systems. (It is connected to a PLTG rather than an LTG because it would be a complete cakewalk for even a novice decker, so the business buys LTG service from another company that runs a firewall with a much tougher system.)
PLTG connection1
1 Gp business data & software1
14 users + slave systems14

System Two: Rating 3 (900,000¥)

This is an Easy system at Green 5/9/9/9/9/9. It has 180 capacity points, and is using 8% of them for its operating system and security.
Green 5/9/8/8/8/810
Four subsystems at +14
83 Gp/connections/users/slaves166

System Three: Rating 3 (900,000¥)

A decker wanted a good system for programming and put together a small run to swipe the system from the above example. Note that it costs only three times as much as the mainframe programming suite (assuming the decker bought it, rather than pirating it from a contact who owed them a big favor). The system is configured for Green-10/10/10/10/10/10, with no connections, 1 user, 1 Gp misc. data & software, no slaves, a mainframe programming utility and capacity for working on programs up to rating 10 and 700Mp.
Green-10/10/10/10/10 20
1 user, 1 Gp data4
Mainframe programming suite16
700Mp program140

System Four: Rating 5 (6.25M¥)

This is an Average system at Orange-8/13/13/13/13/13. It has 500 capacity points, and is using 73% of them for its operating system and security.
Four subsystems at +480
One subsystem at +530
33 Gp/connections/users/slaves134

System Five: Rating 12 (144 M¥)

This is a powerful mainframe designed for a few high-level users to do extremely secure development, at the top end of VR 2.0’s Hard category at Red 12/18/18/18/18/18; it only has room for 18 Gp of non-security code and data. It has 2880 system capacity points, and is using 95% of them for security! A rating 13 system using this configuration could have 80 Gp for non-security purposes, but at the cost of another 25M¥.
3 subsystems at +8864
2 subsystems at +9720
18 Gp/connections/users/slaves144