Move off your AS/400 one call stream at a time Every rule written down first, and every new program proved against the old
Option 1 callsOne call stream
ORD100RTakes the orderOn the IBM iCUS200RChecks creditMoved and provedPRC300RPrices each lineMoved and provedINV400RAllocates stockOn the IBM i
Writes to
ORDHDRORDDTLCUSMSTStart with what still runs on your AS/400 The order desk enters every order on option 1, so choose its route
- Finance
GLMNU 4, 7, 11GL posting, receivables aging, month-end reportsThe close waits on one batch job, and the one person who reruns it - Order desk
ORDMNU 1, 2, 5Order entry, price overrides, credit holdsNew hires spend weeks learning the screens before they take an order - Warehouse
WHSMNU 3, 4Pick lists, stock moves, cycle countsPick lists are printed at seven and are out of date by nine - Purchasing
PURMNU 1, 6Purchase orders, supplier lookupsSupplier confirmations arrive as PDFs and are keyed in by hand - Customer service
CSRMNU 2Order status, returnsCustomers wait on hold while three screens are checked - IT
Nightly batchRPG changes, CL jobs, file transfersEvery change waits on the two people who know the code
Then choose a route off your AS/400 AI is proven at reading old code, not at converting it end to end
Stay and extend
Stays on the IBM iRight when it works and rarely changes. You still need RPG skills to run it.
Rehost
An IBM i in someone else's data centerYour hardware goes away. The RPG, and the skills problem, stay.
Convert by tool
Generated Java nobody wroteFast on paper. Nobody on your team can read the code it produces.
Rebuild stream by stream
Your new stack, one stream at a timeSlower to start, and every stream is checked against the old system first.
Research: Gartner, October 2026, on AI in legacy modernization.
For order entry, a converter would turn ORD100R into Java nobody on your team wrote.
Prove each new program against the AS/400 Field by field, on months of real orders like 4471209, before anyone switches
How RapidIT reads your IBM iIBM i · ORDHDRNew stack · orders
ORDNO4471209=Order number4471209CUSNO210384=Customer210384ORDDT20261019=Order date20261019PRCLSTB12=Price listB12DSCPCT12.50=Discount12.50CRDHLDN=Credit holdNWHSCDNJ=WarehouseNJORDTOT4318.75=Order total4318.75
Order 4471209 · option 1, run on both0 differences
- Every rule is written down firstYour people read each rule in plain words and correct the ones the code got wrong.
- Old and new run on the same ordersA stream switches over only when months of real records match.
- The IBM i stays the system of recordUntil you switch a stream over, nothing changes for the people who use it.
- We turn down a big-bang rewriteAnd we won't hand you code from a converter that nobody can read.
Then move each AS/400 stream in the order it pays Order entry is being proved now, while its experts are still here
Pricing
Switched over
Credit check
Switched over
Order entry
Being proved
Stock allocation
Planned
Invoicing
Planned
GL posting
Stays on the IBM i
69%of IBM i teams name skills a top concern, up from 45% in 2020Fortra, 2026 IBM i Marketplace Survey
On our report every month
- Call streams switched over
- Rules written down and agreed
- Records that match the IBM i
- Programs still on the IBM i
Tell us what still runs on your AS/400
We'll map one call stream and write its rules down in five days, and you keep the map either way.